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Trophic Dynamics of Mercury in the Baltic Archipelago Sea Food Web: The Impact of Ecological and Ecophysiological Traits
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Contaminants in Aquatic and Terrestrial Environments

Trophic Dynamics of Mercury in the Baltic Archipelago Sea Food Web: The Impact of Ecological and Ecophysiological Traits
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  • Riikka K. Vainio*
    Riikka K. Vainio
    Department of Biology, University of Turku, FI-20014 Turku, Finland
    *Email: [email protected]
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    Orcidhttps://orcid.org/0000-0003-2649-6799
  • Veijo Jormalainen
    Veijo Jormalainen
    Department of Biology, University of Turku, FI-20014 Turku, Finland
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  • Rune Dietz
    Rune Dietz
    Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
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  • Toni Laaksonen
    Toni Laaksonen
    Department of Biology, University of Turku, FI-20014 Turku, Finland
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  • Ralf Schulz
    Ralf Schulz
    iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, DE-76829 Landau, Germany
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    Orcidhttps://orcid.org/0000-0002-6348-6971
  • Christian Sonne
    Christian Sonne
    Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
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  • Jens Søndergaard
    Jens Søndergaard
    Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
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  • Jochen P. Zubrod
    Jochen P. Zubrod
    iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, DE-76829 Landau, Germany
    Zubrod Environmental Data Science, Friesenstrasse 20, DE-76829, Landau, Germany
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  • Igor Eulaers*
    Igor Eulaers
    Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
    Norwegian Polar Institute, FRAM Centre, Postboks 6606 Stakkevollan, NO-9296 Tromsø, Norway
    *Email: [email protected]
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Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2022, 56, 16, 11440–11448
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https://doi.org/10.1021/acs.est.2c03846
Published August 3, 2022

Copyright © 2022 The Authors. Published by American Chemical Society. This publication is licensed under

CC-BY 4.0 .

Abstract

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We investigated trophic dynamics of Hg in the polluted Baltic Archipelago Sea using established trophic magnification (TMFs) and biomagnification factors (BMFs) on a comprehensive set of bird, fish, and invertebrate species. As different ecological and ecophysiological species traits may affect trophic dynamics, we explored the effect of food chain (benthic, pelagic, benthopelagic) and thermoregulatory strategy on trophic total Hg (THg) dynamics, using different approaches to accommodate benthopelagic species and normalize for trophic position (TP). We observed TMFs and most BMFs greater than 1, indicating overall THg biomagnification. We found significantly higher pelagic TMFs (3.58–4.02) compared to benthic ones (2.11–2.34) when the homeotherm bird species were excluded from models, but not when included. This difference between the benthic and pelagic TMFs remained regardless of how the TP of benthopelagic species was modeled, or whether TMFs were normalized for TP or not. TP-corrected BMFs showed a larger range (0.44–508) compared to BMFs representing predator–prey concentration ratios (0.05–82.2). Overall, the present study shows the importance of including and evaluating the effect of ecological and ecophysiological traits when investigating trophic contaminant dynamics.

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Keywords

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Synopsis

Ecophysiological and ecological traits impact the output of established models for trophic contaminant dynamics, potentially having consequences for regulatory decisions based thereon.

1. Introduction

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Trophic dynamics of contaminants that show biomagnification potential have traditionally been investigated using trophic magnification factors (TMFs) and biomagnification factors (BMFs). (1) TMFs measure the average increase in contaminant concentration per trophic level, often proxied by bulk stable nitrogen isotopes (δ15N) due to their characteristic trophic enrichment. (2) BMFs in turn measure the increase in contaminant concentration from prey to predator. However, species’ ecological and ecophysiological traits, such as food chain origin, trophic position, and thermoregulatory strategy, may cause variation in the underlying ecological and contaminant variability when studying the trophic dynamics of contaminants, highlighting the need for trait-based modeling of contaminant dynamics. (3) Nonetheless, risk assessment modeling, typically using such TMFs and BMFs, does not commonly take into account such species traits nor their potential impact on modeling outcomes.
Ecotoxicological studies on marine systems have indicated that contaminant loadings and pathways differ between benthic and pelagic food chains due to for example differences in bioavailability. (4−8) Moreover, often food chains are assumed linear and discrete, while generalist species often feed on prey residing at multiple trophic positions or in different food chains, which may in fact be closely interlinked (for example benthopelagic coupling). Aside from all ecological species characteristics complicating practical discretization of food chains and their composing trophic positions, species exhibit ecophysiological traits, such as thermoregulation and respiration, that influence contaminant bioaccumulation and biomagnification. Indeed, species-differences in thermoregulatory strategy, resulting in differences in metabolism and energy requirements, can cause homeotherm species to accumulate higher contaminant concentrations than poikilotherms. (9−11) In fact, BMFs are currently approached with multiple different formulas, (12) some formulas normalizing for trophic position differences for the predator–prey pairs, while some do not. Even so, such potential impacts of different species-traits on BMFs, or TMFs, have not been consequently reported or robustly investigated for their importance when studying food web dynamics of contaminants.
The Baltic Sea is particularly susceptible to pollution, due to its geophysical location and hydrological properties (13) and has a well-known legacy for persistent contaminants that typically show biomagnification. (14,15) Among a plethora of hazardous substances found in the Baltic Sea is mercury (Hg (14)), for which emissions have increased dramatically since the Industrial Revolution. (16) Mercury is environmentally persistent, and concentrations are found to be elevated in most Baltic Sea basins (17) and readily bioavailable to the lower functional groups of the food web especially as organic methylmercury (MeHg), resulting in Hg bioaccumulation in higher trophic species and ultimately Hg biomagnification through food chains. (18)
Here we investigate the trophic dynamics of total Hg (THg) in benthic and pelagic food chains of the Baltic Archipelago Sea, using established TMFs and BMFs on a comprehensive set of species (n = 30), across different functional groups, that are key in this low diversity ecosystem. To investigate the impact of different species traits on trophic magnification models, we explored the effect of two ecological traits, i.e., the trophic position food chain origin (benthic, pelagic, benthopelagic) and one ecophysiological trait, i.e., thermoregulatory strategy (homeotherm, poikilotherm) on trophic THg dynamics, using different approaches to accommodate benthopelagic species and normalizing for trophic position (TP).

2. Materials and Methods

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2.1. Sample Collection

We collected samples of birds, fish, and invertebrates during the period 2017–2019, except for the extended time frame (2013–2019) for white-tailed eagle (Haliaeetus albicilla), in the Archipelago Sea, a Baltic Sea basin at the southwestern coast of Finland (Figure 1).

Figure 1

Figure 1. Map of the sampling locations.

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The Archipelago Sea is one of the largest archipelagos and is a shallow brackish water ecosystem with low salinity, inhabited by both marine and freshwater species. Information on the sampling methods, collection times, tissues used for chemical analysis, and use of composite versus individual samples are presented in Table S1. We measured body length for invertebrates and fish, and individual fish mass was recorded when possible (Table S2). All birds were dissected for muscle. From larger fish species the dorsal fillet was dissected, while from smaller species the intestinal tract was removed, except from lesser sand eel (Ammodytes tobianus) and sand goby (Pomatoschistus minutus), before homogenization of the entire individual using a shear mixer. We pooled individual invertebrates sampled at the same location to constitute a composite sample with sufficient mass for chemical analysis. We transported all samples under cool and dark conditions during field collection and stored them at −20 °C prior to sample preparation for chemical analysis, prior to which samples were freeze-dried at −50 °C, gravimetrically determined for its dry matter, and finally homogenized using pestle and mortar.

2.2. Mercury Analysis

The analysis for total mercury was performed using a direct mercury analyzer (DMA-80, Milestone, Italy) at the accredited Trace Element Laboratory at Department of Ecoscience, Aarhus University, following the US-EPA Method 7473 (19) during the period 2019–2021. The analytical quality was controlled by concurrently analyzing aqueous standard solutions (10 ng and 100 ng of Hg, prepared from 1000 ± 4 mg L–1 stock solution, Sigma-Aldrich, Switzerland), procedural blanks, duplicates, and Certified Reference Material (DORM-4; fish protein from the National Research Council, Canada; 0.412 ± 0.036 μg Hg g–1 dry weight, dw). Measurements were subsequently corrected for instrumental drift using results from the aqueous 10 and 100 ng standards applied to the low- and high-concentration cell, respectively (drift was always < 10%). All samples were corrected for concurrent blanks (<0.1 ng). The measured recovery long-term percentage of the DORM-4 was 102 ± 6% (mean ± SD; n = 284 during 2019–2021). This shows satisfactory accuracy and a precision (extended analytical uncertainty) (2 SD) of ca. 10% for the analyses. The laboratory is accredited by the Danish Accreditation Fond DANAK following ISO 17025 to DMA-80 analyses of Hg in biota with a detection limit of 0.001 μg g–1 dw. As part of the laboratory QA/QC, the lab participates twice a year in the international laboratory performance study program QUASIMEME (www.quasimeme.org). The participation has proved excellent long-term measurement accuracy and precision (n = 15 during 2017–2021; assigned concentration from 0.009 to 0.931 μg g–1 dw; Z-scores from −1.0 to 0.7 with a mean of −0.1).

2.3. Stable Isotope Analysis

The stable isotope analysis was carried out at the Stable Isotope Lab of the University of Koblenz-Landau (Germany). Ratios of stable nitrogen isotopes (15N:14N) were determined on a freeze-dried and homogenized subsample (mean ± SD: 1.48 ± 0.06 mg) using a Flash 2000 HT elemental analyzer coupled via a ConFlo IV interface to a Delta V Advantage isotope ratio mass spectrometer (all Thermo Fisher Scientific, Bremen, Germany). The stable nitrogen isotope values are reported following best practices suggested by Bond and Hobson (20) and are relative to their respective international measurement standard of atmospheric N2. Internal reference material (casein) was measured concurrently in duplicate every 10 samples, revealing an imprecision (±SD) ≤ 0.06 ‰.

2.4. Data Analysis

To investigate the effect of ecological and ecophysiological traits on trophic magnification of THg, we categorized the study species, based on their diet, for their food chain (18 benthic, five pelagic, and seven benthopelagic species) and thermoregulatory strategy (three homeotherm, 27 poikilotherm). Rather than relying on the empirical stable isotope values we used literature on the studied species (see Supporting Information for full reference list) to define species to be pelagic or benthic, when mainly feeding in a food chain depending on pelagic or benthic basal energy sources, respectively, or to be benthopelagic when feeding in both.
We calculated the TP of an individual of a benthic and pelagic species following Post: (21)
(1)
where the trophic enrichment factor (TEF) Δ15N was set at 3.40, as recommended by Borgå et al., (1) and where δ15Nbaseline is the δ15N value for the chosen benthic or pelagic primary consumer species (assumed to feed at TP = 2), that is, Gammarus spp. and zooplankton, respectively for benthic and pelagic species. Primary consumer species are preferred as food chain baselines as primary producers’ δ15N values can show large spatiotemporal variability due to seasonal variation in growth rate and different nutrient inputs in different locations. (21) Due to this variability, we omitted primary producers from the trophic magnification models (See Supporting Information for more on the primary producers).
The calculation of TPs for benthopelagic species can however not follow this one-source model, as mixed feeding on both benthic and pelagic prey comes along with dependency on two δ15N baselines. Because of this, we calculated the TP for individuals of benthopelagic species following two approaches. In the first approach, we assumed that the benthopelagic species feeds entirely in either benthic or pelagic habitat, that is, from one basal energy source, and therefore the above-described one-source TP calculation was used for both food chains separately. In the second approach, we used a two-source model, assuming that the benthopelagic species feeds in both benthic and pelagic habitats, calculating the TP following the two-source formula outlined by Post: (21)
(2)
where δ15Nbaseline_B and δ15Nbaseline_P are the δ15N values of benthic and pelagic baselines, respectively. As the actual proportions in which benthopelagic species feed from benthic and pelagic food chains are unknown, we set the proportion of feeding from the first food chain to α = 0.50.
For birds, a TEF of Δ15N = 2.4 is more appropriate to represent trophic enrichment between bird tissue and that of their prey. (22) Hence, we calculated TPs for benthic common eiders in the one-source model following Hop et al.: (9)
(3)
while TPs for the benthopelagic white-tailed eagle and great cormorant were calculated after adaptation from Hop et al. (9) and Post: (21)
(4)
with α = 0.50. As the δ15N signal of whole fish and muscle tissue can show small differences, the TP estimated for whole fish might differ 0–0.6 trophic levels compared to TP determined from the muscle tissue. (23,24)
We calculated TMFs, also referred to as food web magnification factors (FWMFs), separately for the benthic and pelagic food chains, using both one-source and two-source models due to the included benthopelagic species. We used a linear mixed model with log10[THg dw] as dependent variable, TP or δ15N as independent variable, and species as a random variable due to unbalanced sample sizes across the studied species. Using the slope b of each fitted model we calculated the TMF following
(5)
The slope of the regression measures the increase in THg concentrations with the calculated TPs across the food chain, while the intercept represents the biological and environmental factors that determine the input of THg into the food chain at its base. (1) We used dw concentrations due to smaller variation of wet weight concentrations negatively effecting the reliability of the models. To assess the impact of homeotherm species on the trophic magnification models, we repeated all models excluding the three bird species. To compare the goodness of fit for the models, we calculated coefficients of determination for each model according to Nagawa et al.: (25) marginal Rm2, which represents the total variance explained by the fixed effects, and conditional Rc2, representing proportion of variance explained by both fixed and random effects. Differences in the slopes and intercepts between the benthic and pelagic food chain models were tested using a Welch’s t test.
Finally, to assess the effect of normalizing BMFs for TP, we calculated BMFs for all likely predator–prey pairs, based on literature recordings of the diet of the species (see Supporting Information), with normalization for TP:
(6)
and without:
(7)
The difference between the values produced by the two BMF approaches was calculated for each predator–prey pair by taking the absolute value of the subtraction of the BMFTP and BMFR. Due to consisting of only one individual, we omitted Atlantic salmon from the BMF calculations. Full BMF results with Atlantic salmon can be found in Tables S4–S7.

3. Results

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Summary statistics for δ15N, TP, and THg for all studied species are given in Table 1, and the extended summary statistics are given in Table S3. All TMFs exceeded one, indicating food web magnification (Figure 2; Table 2).

Figure 2

Figure 2. Linear regressions between log10[THg dw] (μg g–1) and trophic position for (A) benthic habitat (all species), (B) benthic habitat (no birds), (C) pelagic habitat (all species), and (D) pelagic habitat (no birds). The solid lines are for regression of the one-source model (eqs 1 and 3), while the dashed lines are for the two-source model (eqs 2 and 4).

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Table 1. Mean ± SD Values for δ15N, TP, and THg Concentrations (μg g–1 ww and dw) for the Studied Species, Grouped According to Their Food Chaina
scientific namecommon namenδ15NTPHg dwHg ww
Pelagic
Ammodytes tobianuslesser sand eel1*+10.732.950.0140.0027
Clupea harengusherring10+13.00 ± 2.393.61 ± 0.700.15 ± 0.170.035 ± 0.041
Coregonus albulavendace2+12.29 ± 0.223.41 ± 0.060.087 ± 0.0130.018 ± 0.003
Salmo salarAtlantic salmon1+13.003.610.150.055
zooplankton 3*+7.52 ± 0.142.00 ± 0.040.0059 ± 0.00150.0006 ± 0.0002
Benthic
Somateria mollissimacommon eider13+10.32 ± 0.794.11 ± 0.230.67 ± 0.310.17 ± 0.09
Abramis bramacommon bream6+13.80 ± 1.374.84 ± 0.400.17 ± 0.060.042 ± 0.018
Gobius nigerblack goby5+11.80 ± 0.274.25 ± 0.080.028 ± 0.00870.0060 ± 0.0019
Gymnocephalus cernuaEurasian ruffe10+14.40 ± 0.695.01 ± 0.200.13 ± 0.080.026 ± 0.017
Myoxocphalus quadricornisfourhorn sculpin5+16.659 ± 0.755.66 ± 0.220.45 ± 0.380.083 ± 0.055
Neogobius melanostomusround goby10+10.45 ± 0.643.85 ± 0.190.018 ± 0.0050.0044 ± 0.0020
Pomatoschistus minutussand goby1*+13.734.820.0190.0045
Rutilus rutiluscommon roach10+11.67 ± 1.584.21 ± 0.460.15 ± 0.060.035 ± 0.014
Zoarces viviparusviviparous eelpout10+12.78 ± 0.494.54 ± 0.140.066 ± 0.0360.015 ± 0.008
Gammarus spp. 6*+4.15 ± 0.842.00 ± 0.250.018 ± 0.0260.0037 ± 0.0050
Idotea spp. 4*+4.25 ± 1.222.03 ± 0.360.0060 ± 0.00350.0016 ± 0.0010
Macoma balthicaBaltic clam4*+8.70 ± 0.293.34 ± 0.090.037 ± 0.0060.0074 ± 0.0013
Mytilus edulisblue mussel9*+7.16 ± 1.402.88 ± 0.410.037 ± 0.0130.0059 ± 0.0023
Palaemon adpersus 1+9.903.690.00860.0019
Palaemon elegans 1*+8.443.260.00910.0022
Rhithropanopeus harrisii 1*+8.243.200.0280.0071
Saduria entomon 2*+10.55 ± 0.793.88 ± 0.230.05 ± 0.030.016 ± 0.014
Theodoxus fluviatilis 3*+4.29 ± 0.532.0 ± 0.160.0048 ± 0.00500.0021 ± 0.0022
Benthopelagic
Haliaeetus albicillawhite-tailed eagle7+12.09 ± 1.833.64 ± 0.54 (P)1.9 ± 1.70.51 ± 0.34
4.63 ± 0.54 (B)
4.13 ± 0.54 (T)
Phalacrocorax carbogreat cormorant6+14.48 ± 1.864.34 ± 0.55 (P)1.3 ± 1.00.35 ± 0.27
5.33 ± 0.55 (B)
4.84 ± 0.55 (T)
Coregonus lavaretuscommon whitefish2+11.85 ± 0.163.27 ± 0.05 (P)0.084 ± 0.0490.019 ± 0.011
4.26 ± 0.05 (B)
3.77 ± 0.05 (T)
Esox luciusnorthern pike9+15.84 ± 0.464.45 ± 0.13 (P)0.68 ± 0.430.15 ± 0.09
5.44 ± 0.13 (B)
4.9 ± 0.13 (T)
Gasterosteus aculeatusthree-spined stickleback6+11.52 ± 0.473.18 ± 0.14 (P)0.039 ± 0.0180.010 ± 0.004
4.17 ± 0.14 (B)
3.67 ± 0.14 (T)
Osmerus eperlanusEuropean smelt10+12.78 ± 0.653.55 ± 0.22 (P)0.12 ± 0.080.024 ± 0.017
4.54 ± 0.19 (B)
4.04 ± 0.19 (T)
Perca fluviatilisEuropean perch10+13.73 ± 1.683.83 ± 0.49 (P)0.48 ± 0.380.095 ± 0.070
4.82 ± 0.49 (B)
4.32 ± 0.49 (T)
a

The TPs for benthopelagic species are calculated to comply with either the pelagic (P) or benthic (B) food chain baseline species both using a one-source model (eqs 1 and 3), or to accommodate both baseline species, using a two-source model (T) (eqs 2 and 4). Pooled samples are marked with an asterisk (∗).

Table 2. Statistical Output of Linear Models and the Resulting TMFs for THg (μg g–1 dw) in the Archipelago Sea, Accommodating Different Configurations to Test the Impact of the Species Traits Trophic Position, Food Chain Origin, and Thermoregulatory Strategya
modelnRm2Rc2pintercept (SE)slope (SE)TMF
Pelagic Food Chain
one-source700.140.78<0.01–2.15 (0.34)0.36 (0.08)2.27
one-source (no birds)540.550.70<0.01–3.15 (0.31)0.60 (0.09)4.02
two-source700.260.76<0.01–2.33 (0.32)0.38 (0.08)2.38
two-source (no birds)540.590.73<0.01–3.13 (0.30)0.55 (0.08)3.58
δ15Nb700.110.80<0.01–2.14 (0.36)0.10 (0.03)1.26
δ15N (no birds)b540.550.70<0.01–3.28 (0.33)0.18 (0.06)1.51
Benthic Food Chain
One-source1540.110.80<0.01–2.12 (0.29)0.23 (0.07)1.69
One-source (no birds)1250.420.71<0.01–2.81 (0.25)0.37 (0.06)2.34
Two-source1540.060.82<0.01–1.96 (0.30)0.19 (0.07)1.56
Two-source (no birds)1250.290.71<0.01–2.61 (0.28)0.32 (0.07)2.11
δ15Nb1540.080.81<0.01–1.87 (0.25)0.06 (0.02)1.15
δ15N (no birds)b1250.460.71<0.01–2.52 (0.21)0.11 (0.02)1.28
a

The TP of benthopelagic species was estimated using only pelagic or benthic baseline species (one-source model, eqs 1 and 3) or both (two-source model, eqs 2 and 4). n = sample size, Rm2 = marginal coefficient of determination, Rc2 = conditional coefficient of determination, p = significance for the slope, SE = standard error.

b

Note that the TMFs for the models using δ15N represent THg biomagnification per unit increase of δ15N (‰) instead of per trophic level.

We did not observe statistically significant differences between the pelagic one- and two-source model regardless of whether homeotherms were included or not (−0.38 ≤ t ≤ 0.44; 0.66 ≤ p ≤ 0.97). Similarly, we did not observe differences between benthic one- and two-source models with or without the homeotherms (−0.54 ≤ t ≤ 0.47; 0.59 ≤ p ≤ 0.71). The slopes or intercepts did not differ between the respective benthic models or the pelagic two-source models with or without the homeotherms (−0.21 ≤ t ≤ 1.76; 0.08 ≤ p ≤ 0.83; pelagic two-source: −1.57 ≤ t ≤ 1.76; 0.08 ≤ p ≤ 0.12). However, there was a difference between both slopes (t120 = −2.06; p = 0.04) and intercepts (t120 = 2.19; p = 0.03) for the pelagic one-source models with and without the homeotherms. We did not find differences between the benthic and pelagic models, irrespective of the one- or two-source approach, when homeotherms were included (−1.73 ≤ t ≤ 0.82; 0.09 ≤ p ≤ 0.96). There were also no differences between the model intercepts for the benthic and pelagic food chains, neither using a one-source model (t175 = 0.85; p = 0.40) nor a two-source one (t175 = 1.28; p = 0.20) when homeotherms were excluded.
However, in the models excluding homeotherm bird species, there was a significant difference in the slopes between the pelagic and benthic one-source (t175 = −2.24; p = 0.03) and two-source models (t175 = −2.20; p = 0.03). Regression slopes showed to be steeper in the pelagic food chain in both cases (Table 2). There was also a significant difference between benthic and pelagic slopes (t175 = −2.24; p = 0.03) as well as between the intercepts (t175 = −1.94; p = 0.05) of the TMFδ15N when excluding birds. Again, the slope showed to be steeper in the pelagic food chain, while intercept was higher in the benthic food chain (Table 2). Omitting birds from the models increased the explanatory power (Rm2; Table 2) compared to the respective models including these homeotherm species.
All obtained BMFs calculated using eqs 6 and 7 are given in Tables S4–S7. We observed 95.8% of BMFTP (eq 6) and 91.5% of BMFR (eq 7) to be greater than 1, indicating overall biomagnification. For homeotherms, we observed a range of BMFTP = 4.40–508 and BMFR = 1.48–56.8, while for poikilotherms BMFTP = 0.44–33.5, and BMFR = 0.19–82.2, values of BMFTP, but not BMFR being higher for homeotherms than poikilotherms. For pelagic predators, BMFTP = 1.61–9.35 and BMFR = 2.11–14.4, for benthic predators BMFTP = 0.44–30.9 and BMFR = 0.19–77.6, and for benthopelagic predators BMFTP = 1.61–508 and BMFR = 1.48–82.2, with highest BMFs in both cases found in the benthopelagic species, followed by benthic and pelagic species. Higher variation was observed for the obtained BMFTP (eq 6; mean ± SD = 14.5 ± 45.4; range, 0.44–508; Figure 3A), than for BMFR (eq 7; 11.2 ± 13.4; 0.19–82.2; Figure 3B). There was high variability in the difference between BMFTP and BMFR for the same predator–prey pair (mean ± SD = 11.5 ± 44.0; range, 0.004–494.2), the difference being greater than 10 in 19.9% of the pairs. The denominator in eq 6, that is, the normalization for TP, also was a cause for 9.6% of the predator–prey pairs negative BMFTP (removed from Figure 3A) due to the predator’s TP being lower than that of its prey (see Discussion in the Supporting Information).

Figure 3

Figure 3. Heatmap of biomagnification factors (BMFs) for relevant predator–prey pairs (A) normalized for TP (eq 6) or (B) not (eq 7). Negative BMF values were removed.

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4. Discussion

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We investigated the impact of two ecological traits, trophic position and food chain origin, and an ecophysiological trait, thermoregulatory strategy, on established risk assessment modeling approaches, that is, TMFs and BMFs, to study trophic contaminant dynamics of mercury in the Baltic Archipelago Sea. Overall, TMFs and BMFs showed THg biomagnification to be affected by distinguishing food chains and the presence of homeotherm species. We also found most BMFs to be highly variable between different predator–prey pairs and formulas of calculation.
For both the benthic and pelagic food chains large positive TMF values showed strong THg food web magnification. The observed TMFδ15N values for the pelagic food chain (1.28–1.51) were similar to the TMFδ15N value of 1.50 reported for a pelagic food chain of zooplankton, Mysis spp., and herring in the Baltic Sea. (26) The trophic magnification slopes on δ15N in our study (0.06–0.18) also matched the average of all sites (mean ± SD: 0.16 ± 0.11), temperate sites (0.17 ± 0.10), and marine coastal sites (0.19 ± 0.08) evaluated in a worldwide meta-analysis by Lavoie et al. (27) The number of trophic levels (TPtop predator – TPbaseline) in both benthic (3.7) and pelagic (2.9) food chains in our study included more trophic levels than the studies (mean ± SD 1.7 ± 0.7) included in the same meta-analysis. (27) However, we found the TMFs derived separately for the benthic and pelagic food chains of the Archipelago Sea to reveal higher trophic magnification of THg in the pelagic food chain when excluding birds. This result is robust as it remained independently of how TPs of benthopelagic species were modeled. Similar to our study, higher TMFs in the pelagic food chain compared to those in the benthic one have been reported in the Gulf of St. Lawrence, Canada, (4) and Santos continental shelf, Brazil. (6) Pelagic pathways have been suggested to be more efficient in transferring highly bioaccumulative and biomagnifying MeHg compared to transfer from sediments, MeHg being more readily bioavailable in the pelagic food chain. (28,29) Although studies have shown both inorganic and organic species of Hg being capable of being transferred through the diet and assimilated into organisms’ tissue, both the rate of absorption and assimilation are higher for MeHg than inorganic species of Hg, (30) leading to higher rates of both bioaccumulation and biomagnification for MeHg, possibly contributing to the higher TMF observed for the pelagic food chain. Also, although the THg concentrations at the base of both benthic and pelagic food chains of our study were similar and dietary pathways dominate the Hg uptake in higher trophic levels (for example refs (30and31)), possible additional uptake of Hg through bioconcentration may partly explain the difference in TMFs between the benthic and pelagic food chains. These possibly different pathways of Hg into the benthic and pelagic food chain and proportions of MeHg should be further investigated to unravel their effect on the trophic dynamics of Hg. However, trophic contaminant dynamics between food chains are system-specific due to differences in for example physiochemical properties of the environment, and thus inherent variability in the resulting contamination pathways. Our results demonstrate the importance of investigating differences in trophic transfer of contaminants between different food chain pathways to better understand the contaminant dynamics.
In the present study, we modeled the TPs of benthopelagic species in two ways: assuming linearity of the food chain with its composing species feeding from only one basal energy source and allowing for the possibility of cross-food chain feeding depending on two basal energy sources. Often TP and trophic magnification models based thereon accommodate only one baseline species. However, most generalist and mobile species forage in different environments and food chains. Prey-switching can happen due to availability and ontogeny, and individuals can move between environments between seasons and stages of life cycle. (32−34) Recently, studies have investigated the coupling of benthic and pelagic systems (35) suggesting that benthic and pelagic habitats are coupled more closely in various ways than previously assumed. (36) The modeling approach (one- or two-source model) for the benthopelagic species did not affect the TMFs. While our two-source model approach, assuming benthopelagic species feeding 50% in either food chain, is perhaps still not entirely accurate as actual consumer-specific prey proportions would show, it offers a more ecologically realistic solution to accommodate species that show cross-food chain feeding strategies when using bulk stable isotopes for TP estimation. Moreover, applying an analysis for compound-specific stable isotopes (37,38) may provide additional insights and, perhaps, an even more robust assessment of the trophic dynamics of Hg in the studied food web.
Homeotherm species may accumulate higher concentrations of recalcitrant contaminants, such as Hg, than poikilotherms due to higher energy requirements demanding higher food consumption and thus intake of contaminants. (1,9) Moreover, as long-lived species, birds bioaccumulate recalcitrant contaminants during their lifetime. (39) Trophic magnification models including homeotherm birds did not show different trophic magnification between the benthic and pelagic food chain, in sharp contrast to the models excluding homeotherms. Moreover, all trophic magnification models without homeotherm species showed better statistical fit (Rm2) compared to models including homeotherms. However, omitting the homeotherm birds affected TMFs only for the pelagic one-source model, with TMF being higher without the birds. We found THg concentrations in homeotherms to be relatively elevated in comparison to species from other functional groups exhibiting similar TP. Similarly, Wang et al. (10) modeled MeHg biomagnification in floodplain food webs and found that the regression line for homeotherms had a higher intercept than the one for poikilotherms. While such a comparison should be made with precaution, as the present study cannot provide insight on MeHg dynamics, our findings also seem to suggest that the impact of thermoregulatory strategy on both within food chain and between food chain TMF estimates merits future consideration of designing and comparing trophic contaminant magnification modeling attempts.
More than 90% of all BMFs exceeded 1, further demonstrating THg biomagnification in the Archipelago Sea food web. For BMFTP, homeotherms had a larger range and higher maximum values than poikilotherms, while for BMFR ranges of homeotherms and poikilotherms were similar. When comparing BMFs across food chains, the highest BMFTP and BMFR were found for benthopelagic predators, and the lowest ones were found for pelagic predators. The total range of BMFs was large, especially BMFTP. This was not only due to differences in THg concentrations between predator and its prey, but also due to a small TP difference: small TP differences are therefore observed to inflate BMFTP. Conversely, large differences in δ15N-derived TPs may also lead to underestimation of the biomagnification potential. Large disparities in BMFs with and without the normalization for TPs may indicate that the actual diet of the predator includes also other sources of contamination than the prey used for calculating BMFs, (40) while also other factors, such as disparity in temporality, may affect BMFs. Currently, there seem to be no unbiased BMF estimations as each model (see Franklin (12)) has trade-offs between ecological reality and statistical applicability. Different ecological and physiological factors, such as uncertainties in species feeding ecology and metabolism, also affect BMFs, and cause variability in BMFs of the same contaminants between different studies. (12) Indeed, our results show that different ecological and ecophysiological species traits, such as the here studied food chain origin, TP, and thermoregulatory strategy, introduce uncertainty in BMF comparisons making comparisons within and across studies more difficult. Our finding of highly variable BMFs supports the recommendation of using TMFs rather than BMFs, as TMFs represent the average biomagnification across the food chain and are less likely to be affected by individual species traits than the BMFs. (41)
A recent risk assessment of THg concentrations on the Baltic Sea (42) showed the fish and bivalves being at low risk of Hg mediated health effects, while in white-tailed eagles the risk of negative health effects was assessed to be moderate to high. However, the results of the risk assessment should be taken as indicative, as variation in the proportions of highly toxic MeHg between both species and individuals can occur. (42) Also, climate change mediated increases in runoff combined with other factors, such as shorter icing period, may increase Hg fluxes into the Baltic Sea as well as Hg bioavailability, (43) altogether potentially increasing the loadings and changing the dynamics of Hg in the food web. Because of these concerns, it is important to understand the role of ecological and ecophysiological traits on trophic contaminant dynamics, as well as the vulnerability of current models used for regulatory decisions. Moreover, the novel functional ecological understanding and comparative model framework of the present study should be further investigated for implications due to Hg speciation dynamics.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c03846.

  • Methods and discussion of primary producer and trophic positions of the species, literature references on the diet of the study species, Tables S1–S7 with additional information on the sampling, summary statistics, and full biomagnification factors (PDF)

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Author Information

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  • Corresponding Authors
    • Riikka K. Vainio - Department of Biology, University of Turku, FI-20014 Turku, Finland;  Orcidhttps://orcid.org/0000-0003-2649-6799;  Email: [email protected]
    • Igor Eulaers - Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark;  Norwegian Polar Institute, FRAM Centre, Postboks 6606 Stakkevollan, NO-9296 Tromsø, Norway;  Email: [email protected]
  • Authors
    • Veijo Jormalainen - Department of Biology, University of Turku, FI-20014 Turku, Finland
    • Rune Dietz - Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
    • Toni Laaksonen - Department of Biology, University of Turku, FI-20014 Turku, Finland
    • Ralf Schulz - iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, DE-76829 Landau, Germany;  Orcidhttps://orcid.org/0000-0002-6348-6971
    • Christian Sonne - Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
    • Jens Søndergaard - Department of Ecoscience, Aarhus University, Frederiksborgvej 399, Postbox 358, DK-4000 Roskilde, Denmark
    • Jochen P. Zubrod - iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, DE-76829 Landau, Germany;  Zubrod Environmental Data Science, Friesenstrasse 20, DE-76829, Landau, Germany
  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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The study was performed under the project BONUS BALTHEALTH. BONUS BALTHEALTH has received funding from BONUS (Art. 185), funded jointly by the EU, Innovation Fund Denmark (Grants 6180-00001B and 6180-00002B), Forschungszentrum Jülich GmbH, German Federal Ministry of Education and Research (Grant FKZ 03F0767A), Academy of Finland (Grant 311966) and Swedish Foundation for Strategic Environmental Research (MISTRA). Funding was also received from the Turku University Foundation (Grant 080552) and the Finnish Foundation for Nature Conservation and Finnish Cultural Foundation, Varsinais-Suomi Regional fund (Grant 85201728). The authors thank Finnish Natural History Museum, Minna Kivimäki, Olavi Sahlsten, Johannes Sahlsten, Luca Rugiu, Jarmo Väisänen, Aki Perälä, and Lasse Heimo for their help with the sample collection.

References

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    Environmental Science & Technology (2017), 51 (24), 14135-14143CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Habitat is of great importance in detg. the trophic transfer of pollutants in freshwater ecosystems; however, the major factors influencing chem. trophodynamics in pelagic and benthic food webs remain unclear. This study investigated the levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), polycyclic arom. hydrocarbons (PAHs), and substituted PAHs (s-PAHs) in 2 plankton species, 6 invertebrate species, and 10 fish species collected from Lake Dianchi in southern China. Relatively high concns. of PAHs and s-PAHs were detected with total concns. of 11.4-1400 ng/g wet wt. (ww) and 5.3-115 ng/g ww, resp. Stable isotope anal. and stomach content anal. were applied to quant. det. the trophic level of individual organisms and discriminate between pelagic and benthic pathways, and the trophodynamics of the detected compds. in the two food webs were assessed. P,p'-DDE was found to exhibit relatively higher trophic magnification rate in the pelagic food web than in the benthic food web. In contrast, PAHs and s-PAHs exhibited greater diln. rates along the trophic levels in the pelagic food web. The lower species differences of pollutants accumulated in benthic organisms compared to pelagic organisms is attributable to extra uptake via ingested sediment in benthos. The av. uptake proportions of PAHs and s-PAHs via ingested sediment in benthic biotas were estd. to be 31-77%, and that of p,p'-DDE was 46%. The uptake routes are of importance for assessing the trophic magnification potentials of org. pollutants, esp. in eutrophic freshwater ecosystems.
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  9. 9
    Hop, H.; Borga, K.; Gabrielsen, G. W.; Kleivane, L.; Skaare, J. U. Food web magnification of persistent organic pollutants in poikilotherms and homeotherms from the Barents Sea. Environ. Sci. Technol. 2002, 36, 2589– 2597,  DOI: 10.1021/es010231l
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    Food Web Magnification of Persistent Organic Pollutants in Poikilotherms and Homeotherms from the Barents Sea
    Hop, Haakon; Borgaa, Katrine; Gabrielsen, Geir Wing; Kleivane, Lars; Skaare, Janneche Utne
    Environmental Science and Technology (2002), 36 (12), 2589-2597CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Food web magnification of persistent org. pollutants (POPs) was detd. for the Barents Sea food web using δ15N as a continuous variable for assessing trophic levels (TL). The food web investigated comprised zooplankton, ice fauna and fish (poikilotherms, TL 1.7-3.3), and seabirds and seals (homeotherms, TL 3.3-4.2), with zooplankton representing the lowest and glaucous gull the highest trophic level. Concns. of lipophilic and persistent organochlorines were orders of magnitude higher in homeotherms than in poikilotherms. These compds. had significantly higher rates of increase per trophic level in homeotherms relative to poikilotherms, with the highest food web magnification factors (FWMFs) for cis-chlordane and p,p'-DDE. Some compds., such as trans-nonachlor and HCB, had similar rates of increase throughout the food web, whereas compds. that are more readily eliminated (γ-HCH) showed no relationship with trophic level. It is preferable to calc. FWMFs with regard to thermal groups, because the different energy requirements and biotransformation abilities between poikilotherms and homeotherms may give different rates of contaminant increase with trophic level. When biomagnification is compared between ecosystems, FWMFs are preferable to single predator-prey biomagnification factors. FWMFs represent a trophic level increase of contaminants that is av. for the food chain rather than an increase for a specific predator-prey relationship. The Barents Sea FWMFs were generally comparable to those detd. for marine food webs with similar food chain lengths in the Canadian Arctic.
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  10. 10
    Wang, J.; Newman, M. C.; Xu, X.; Liang, L. Higher and more variable methylmercury biomagnification factors for floodplain than the contiguous river (South River, Virginia USA). Ecotoxicol. Environ. Saf. 2013, 92, 191– 198,  DOI: 10.1016/j.ecoenv.2012.04.023
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    Higher and more variable methylmercury biomagnification factors for floodplain than the contiguous river (South River, Virginia USA)
    Wang, Jincheng; Newman, Michael C.; Xu, Xiaoyu; Liang, Lian
    Ecotoxicology and Environmental Safety (2013), 92 (), 191-198CODEN: EESADV; ISSN:0147-6513. (Elsevier B.V.)
    Extending previous trophic transfer studies of the mercury-contaminated South River watershed, predictive models were built for mercury biomagnification in floodplain food webs at two more locations (North Park and Grand Cavern). Four of five models built to date based on methylmercury and δ15N met the a priori requirement for useful prediction (prediction r2≈0.80). An addnl. factor included in models was organism thermoregulatory strategy (poikilothermy or homeothermy). The methylmercury food web biomagnification factors (FWMFs, fold increase per trophic level) for the North Park and Grand Cavern locations were 17.4 (95% CI of 9.5-31.6) and 6.2 (95% CI of 3.5-11.0) resp. FWMF calcd. in 2009 were 9.3 (95% CI of 5.4-16.2) for the Augusta Forestry Center and 25.1 (95% CI of 12.6-50.1) for Grottoes Town Park. The overall South River floodplain FWMF generated by meta-anal. of the four locations was 12.4 (95% CI of 6.8-22.3). These results supported previous findings that the South River floodplain food webs had higher biomagnification factors than the contiguous aquatic food web (4.6, 95% CI of 3.6-5.7). Floodplain FWMFs were also more variable than those of the river.
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  11. 11
    Romero-Romero, S.; Herrero, L.; Fernandez, M.; Gomara, B.; Acuna, J. L. Biomagnification of persistent organic pollutants in a deep-sea, temperate food web. Sci. Total Environ. 2017, 605–606, 589– 597,  DOI: 10.1016/j.scitotenv.2017.06.148
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    11
    Biomagnification of persistent organic pollutants in a deep-sea, temperate food web
    Romero-Romero, Sonia; Herrero, Laura; Fernandez, Mario; Gomara, Belen; Acuna, Jose Luis
    Science of the Total Environment (2017), 605-606 (), 589-597CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Polychlorinated biphenyls (PCBs), polybrominated di-Ph ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were measured in a temperate, deep-sea ecosystem, the Avile´s submarine Canyon (AC; Cantabrian Sea, Southern Bay of Biscay). There was an increase of contaminant concn. with the trophic level of the organisms, as calcd. from stable nitrogen isotope data (δ15N). Such biomagnification was only significant for the pelagic food web and its magnitude was highly dependent on the type of top predators included in the anal. The trophic magnification factor (TMF) for PCB-153 in the pelagic food web (spanning four trophic levels) was 6.2 or 2.2, depending on whether homeotherm top predators (cetaceans and seabirds) were included or not in the anal., resp. Since body size is significantly correlated with δ15N, it can be used as a proxy to est. trophic magnification, what can potentially lead to a simple and convenient method to calc. the TMF. In spite of their lower biomagnification, deep-sea fishes showed higher concns. than their shallower counterparts, although those differences were not significant. In summary, the AC fauna exhibits contaminant levels comparable or lower than those reported in other systems.
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  12. 12
    Franklin, J. How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances. Integr. Environ. Assess. Manag. 2016, 12, 6– 20,  DOI: 10.1002/ieam.1642
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    12
    How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances
    Franklin, James
    Integrated Environmental Assessment and Management (2016), 12 (1), 6-20CODEN: IEAMCK; ISSN:1551-3777. (John Wiley & Sons Inc.)
    This review examines the usefulness of the metrics BMF (biomagnification factor) and TMF (trophic magnification factor), derived from field measurements of the levels of contaminants in naturally occurring biota, for characterizing the bioaccumulation potential ("B") of chems. Trophic magnification factor and BMF values greater than 1.0 are often considered to be the most conclusive indicators of B status, and the TMF criterion has been referred to as the "gold std." for B categorization. Although not wishing to dispute the theor. primacy of field-derived BMFs and TMFs as B metrics, we make the case that, in practice, the study-to-study (and even within-study) variability of the results is so great that they are of very restricted usefulness for assessing B status, at least in the case of the per- and polyfluoroalkyl substances (PFASs), on which we focus here. This conclusion is based on an anal. of the results of 24 peer-reviewed studies reporting field-derived BMFs or TMFs for 14 PFASs, for which BMF values often range over several orders of magnitude from <<1.0 to >>1.0, sometimes even in the same study. For TMFs, the range is a factor of approx. 20 for the most intensely studied PFASs (perfluorooctanoic acid [PFOA] and perfluorooctanesulfonic acid [PFOS]). We analyze the possible causes for such variability: To some extent it results from the differing ways in which the metrics are expressed, but most of the scatter is likely attributable to such factors as nonachievement of the tacitly assumed steady-state conditions, uncertainties in the feeding ecol., the impact of metab. of precursor compds., and so forth. As more trustworthy alternatives to field-derived BMFs and TMFs, we suggest the implementation of dietary BMF studies performed under strictly controlled conditions on aquatic, terrestrial, and avian species, as well as the consideration of measured elimination half-lives, which have been demonstrated to be directly related to BMF values. Integr Environ Assess Manag 2016;12:6-20. © 2015 The Author. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.
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  13. 13
    Reusch, T. B. H.; Dierking, J.; Andersson, H. C.; Bonsdorff, E.; Carstensen, J.; Casini, M.; Czajkowski, M.; Hasler, B.; Hinsby, K.; Hyytiäinen, K.; Johannesson, K.; Jomaa, S.; Jormalainen, V.; Kuosa, H.; Kurland, S.; Laikre, L.; MacKenzie, B. R.; Margonski, P.; Melzner, F.; Oesterwind, D.; Ojaveer, H.; Refsgaard, J. C.; Sandström, A.; Schwarz, G.; Tonderski, K.; Winder, M.; Zandersen, M. The Baltic Sea as a time machine for the future coastal ocean. Sci. Adv. 2018, 4, 8195,  DOI: 10.1126/sciadv.aar8195
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    The Baltic Sea as a time machine for the future coastal ocean
    Reusch, Thorsten B. H.; Dierking, Jan; Andersson, Helen C.; Bonsdorff, Erik; Carstensen, Jacob; Casini, Michele; Czajkowski, Mikolaj; Hasler, Berit; Hinsby, Klaus; Hyytiaeinen, Kari; Johannesson, Kerstin; Jomaa, Seifeddine; Jormalainen, Veijo; Kuosa, Harri; Kurland, Sara; Laikre, Linda; Mackenzie, Brian R.; Margonski, Piotr; Melzner, Frank; Oesterwind, Daniel; Ojaveer, Henn; Refsgaard, Jens Christian; Sandstroem, Annica; Schwarz, Gerald; Tonderski, Karin; Winder, Monika; Zandersen, Marianne
    Science Advances (2018), 4 (5), eaar8195/1-eaar8195/16CODEN: SACDAF; ISSN:2375-2548. (American Association for the Advancement of Science)
    Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, uncertain projections, and a lack of test cases for management. We argue that the Baltic Sea can serve as a time machine to study consequences and mitigation of future coastal perturbations, due to its unique combination of an early history of multistressor disturbance and ecosystem deterioration and early implementation of crossborder environmental management to address these problems. The Baltic Sea also stands out in providing a strong scientific foundation and accessibility to long-term data series that provide a unique opportunity to assess the efficacy of management actions to address the breakdown of ecosystem functions. Trend reversals such as the return of top predators, recovering fish stocks, and reduced input of nutrient and harmful substances could be achieved only by implementing an international, cooperative governance structure transcending its complex multistate policy setting, with integrated management of watershed and sea. The Baltic Sea also demonstrates how rapidly progressing global pressures, particularly warming of Baltic waters and the surrounding catchment area, can offset the efficacy of current management approaches. This situation calls for management that is (i) conservative to provide a buffer against regionally unmanageable global perturbations, (ii) adaptive to react to newmanagement challenges, and, ultimately, (iii) multisectorial and integrative to address conflicts assocd. with economic trade-offs.
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    HELCOM Thematic Assessment of Hazardous Substances 2011–2016; Baltic Marine Environment Protection Commission, 2018; p 157.
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    de Wit, C. A.; Bossi, R.; Dietz, R.; Dreyer, A.; Faxneld, S.; Garbus, S. E.; Hellström, P.; Koschorreck, J.; lohrmann, N.; Roos, A.; Sellström, U.; Sonne, C.; Treu, G.; Vorkamp, K.; Yuan, B.; Eulaers, I. Organohalogen compounds of emerging concern in Baltic Sea biota: Levels, biomagnification potential and comparisons with legacy contaminants. Environ. Int. 2020, 144, 106037,  DOI: 10.1016/j.envint.2020.106037
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    Organohalogen compounds of emerging concern in Baltic Sea biota: Levels, biomagnification potential and comparisons with legacy contaminants
    de Wit, Cynthia A.; Bossi, Rossana; Dietz, Rune; Dreyer, Annekatrin; Faxneld, Suzanne; Garbus, Svend Erik; Hellstroem, Peter; Koschorreck, Jan; Lohmann, Nina; Roos, Anna; Sellstroem, Ulla; Sonne, Christian; Treu, Gabriele; Vorkamp, Katrin; Yuan, Bo; Eulaers, Igor
    Environment International (2020), 144 (), 106037CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
    While new chems. have replaced major toxic legacy contaminants such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), knowledge of their current levels and biomagnification potential in Baltic Sea biota is lacking. Therefore, a suite of chems. of emerging concern, including organophosphate esters (OPEs), short-chain, medium-chain and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs), halogenated flame retardants (HFRs), and per- and polyfluoroalkyl substances (PFAS), were analyzed in blue mussel (Mytilus edulis), viviparous eelpout (Zoarces viviparus), Atlantic herring (Clupea harengus), gray seal (Halichoerus grypus), harbor seal (Phoca vitulina), harbor porpoise (Phocoena phocoena), common eider (Somateria mollissima), common guillemot (Uria aalge) and white-tailed eagle (Haliaeetus albicilla) from the Baltic Proper, sampled between 2006 and 2016. Results were benchmarked with existing data for legacy contaminants. The mean concns. for ΣOPEs ranged from 57 to 550 ng g-1 lipid wt. (lw), for ΣCPs from 110 to 640 ng g-1 lw for ΣHFRs from 0.42 to 80 ng g-1 lw, and for ΣPFAS from 1.1 to 450 ng g-1 wet wt. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected in most species. Levels of OPEs, CPs and HFRs were generally similar or higher than those of polybrominated di-Ph ethers (PBDEs) and/or hexabromocyclododecane (HBCDD). OPE, CP and HFR concns. were also similar to PCBs and DDTs in blue mussel, viviparous eelpout and Atlantic herring. In marine mammals and birds, PCB and DDT concns. remained orders of magnitude higher than those of OPEs, CPs, HFRs and PFAS. Predator-prey ratios for individual OPEs (0.28-3.9) and CPs (0.40-5.0) were similar or somewhat lower than those seen for BDE-47 (5.0-29) and HBCDD (2.4-13). Ratios for individual HFRs (0.010-37) and PFAS (0.15-47) were, however, of the same order of magnitude as seen for p,p'-DDE (4.7-66) and CB-153 (31-190), indicating biomagnification potential for many of the emerging contaminants. Lack of toxicity data, including for complex mixts., makes it difficult to assess the risks emerging contaminants pose. Their occurrence and biomagnification potential should trigger risk management measures, particularly for MCCPs, HFRs and PFAS.
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    HELCOM (2018b) Metals (lead, cadmium and mercury). HELCOM core indicator report.https://helcom.fi/media/core%20indicators/Metals-HELCOM-core-indicator-2018.pdf (accessed 2021-08-20).
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    Morel, F. M. M.; Kraepiel, A. M. L.; Amyot, M. The chemical cycle and bioaccumulation of mercury. Annu. Rev. Ecol Syst 1998, 29, 543– 566,  DOI: 10.1146/annurev.ecolsys.29.1.543
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    US-EPA. Method 7473 (SW-846): Mercury in Solids and Solutions by Thermal Decomposition, Amalgamation, and Atomic Absorption Spectrophotometry, rev. 0; US-EPA: Washington, DC, 1998; 17 pp (https://www.epa.gov/sites/production/files/2015-07/documents/epa-7473.pdf).
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    Nakagawa, S.; Johnson, P. C. D.; Schielzeth, H. The coefficient of determination and intra-class correlation coefficient from generalized linear mixed-effects models revisited and expanded. J. R Soc. Interface 2017, 14, 20170213,  DOI: 10.1098/rsif.2017.0213
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    Nfon, E.; Cousins, I. T.; Järvinen, O.; Mukherjee, A. B.; Verta, M.; Broman, D. Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea. Sci. Total Environ. 2009, 407, 6267– 6274,  DOI: 10.1016/j.scitotenv.2009.08.032
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    Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea
    Nfon, Erick; Cousins, Ian T.; Jaervinen, Olli; Mukherjee, Arun B.; Verta, Matti; Broman, Dag
    Science of the Total Environment (2009), 407 (24), 6267-6274CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
    Mercury (Hg) and 13 other trace elements (Al, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were measured in phytoplankton, zooplankton, mysis and herring in order to examine the trophodynamics in a well-studied pelagic food chain in the Baltic Sea. The fractionation of nitrogen isotopes (δ 15N) was used to evaluate food web structure and to est. the extent of trophic biomagnification of the various trace elements. Trophic magnification factors (TMFs) for each trace element were detd. from the slope of the regression between trace element concns. and δ 15N. Calcd. TMFs showed fundamental differences in the trophodynamics of the trace elements in the pelagic food chain studied. Concns. of Al, Fe, Ni, Zn, Pb and Cd showed statistically significant decreases (TMF < 1) with increasing trophic levels and thus these trace elements tropically dil. or biodilute in this Baltic food chain. Cu, As, Cr, Mn, V, Ti and Co showed no significant relationships with trophic levels. Hg was unique among the trace elements studied in demonstrating a statistically significant increase (TMF > 1) in concn. with trophic level i.e. Hg biomagnifies in this Baltic food chain. The estd. TMF for Hg in this food chain was comparable to TMFs obsd. elsewhere for diverse food chains and locations.
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    Lavoie, R. A.; Jardine, T. D.; Chumchal, M. M.; Kidd, K. A.; Campbell, L. M. Biomagnification of Mercury in Aquatic Food Webs: A Worldwide Meta-Analysis. Environ. Sci. Technol. 2013, 47, 13385– 13394,  DOI: 10.1021/es403103t
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    Biomagnification of Mercury in Aquatic Food Webs: A Worldwide Meta-Analysis
    Lavoie, Raphael A.; Jardine, Timothy D.; Chumchal, Matthew M.; Kidd, Karen A.; Campbell, Linda M.
    Environmental Science & Technology (2013), 47 (23), 13385-13394CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    The slope of the simple linear regression between log10 transformed Hg concn. and stable N isotope values (δ15N), hereafter called trophic magnification slope (TMS), from several trophic levels in a food web can represent the overall degree of Hg biomagnification. We compiled data from 69 studies that detd. total Hg (THg) or MeHg TMS values in 205 aquatic food webs worldwide. Hg TMS values were compared against physicochem. and biol. factors hypothesized to affect Hg biomagnification in aquatic systems. Food webs ranged across 1.7±0.7 (mean ±SD) and 1.8±0.8 trophic levels (calcd. using δ15N from baseline to top predator) for THg and MeHg, resp. The av. trophic level (based on δ15N) of the upper-trophic-level organisms in the food web was 3.7±0.8 and 3.8±0.8 for THg and MeHg food webs, resp. For MeHg, the mean TMS value was 0.24±0.08 but varied from 0.08 to 0.53 and was, on av., 1.5 times higher than that for THg with a mean of 0.16±0.11 (range: -0.19 to 0.48). Both THg and MeHg TMS values were significantly and pos. correlated with latitude. TMS values in freshwater sites increased with dissolved org. C and decreased with total P and atm. Hg deposition. Results suggest that Hg biomagnification through food webs is highest in cold and low productivity systems; however, much of the among-system variability in TMS values remains unexplained. We identify crit. data gaps and provide recommendations for future studies that would improve our understanding of global Hg biomagnification.
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    Chen, C. Y.; Dionne, M.; Mayes, B. M.; Ward, D. M.; Sturup, S.; Jackson, B. P. Mercury bioavailability and bioaccumulation in estuarine food webs in the Gulf of Maine. Environ. Sci. Technol. 2009, 43, 1804– 1810,  DOI: 10.1021/es8017122
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    Mercury Bioavailability and Bioaccumulation in Estuarine Food Webs in the Gulf of Maine
    Chen, Celia Y.; Dionne, Michele; Mayes, Brandon M.; Ward, Darren M.; Sturup, Stefan; Jackson, Brian P.
    Environmental Science & Technology (2009), 43 (6), 1804-1810CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Marine food webs are important links between Hg in the environment and human exposure via consumption of fish. Estuaries contain sediment repositories of Hg and are also crit. habitat for marine fish and shellfish species consumed by humans. MeHg biotransfers from sites of prodn. in estuarine sediments to higher trophic levels via both benthic and pelagic pathways. The authors studied the potential for Hg biotransfer to estuarine food webs across a Hg contamination gradient in the Gulf of Maine. Despite the variation in sediment Hg concns. across sites ( > 100 fold), Hg concns. in biota ranged by only 2-4 fold for each species across sites. Sediment contamination alone explained some variation in Hg and MeHg concns. in biota across sites. However, biogeochem. and ecol. factors also explained significant variation in Hg bioaccumulation across species. Contaminated sites had higher total org. carbon concns. in sediments, which related to a decrease in Hg bioaccumulation (measured as biota-sediment concn. factors). Also, concns. of MeHg were higher in pelagic-feeding than benthic-feeding fauna (detd. from δ13C), indicating the importance of pelagic pathways in transferring MeHg. Lastly, the proportion of total Hg as MeHg increased with trophic level (measured as δ15N). These results reveal the importance of both biogeochem. and ecol. factors in detg. the bioavailability and trophic transfer of MeHg in estuarine food webs.
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    Chen, C. Y.; Borsuk, M. E.; Bugge, D. M.; Hollweg, T.; Balcom, P. H.; Ward, D. M.; Williams, J.; Mason, R. P. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast Unitd States. PLoS One 2014, 9, e89305,  DOI: 10.1371/journal.pone.0089305
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    Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the Northeast United States
    Chen, Celia Y.; Borsuk, Mark E.; Bugge, Deenie M.; Hollweg, Terill; Balcom, Prentiss H.; Ward, Darren M.; Williams, Jason; Mason, Robert P.
    PLoS One (2014), 9 (2), e89305/1-e89305/11, 11 pp.CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
    Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concns. in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concns. in water column particulate material, but not in sediments, were predictive of MeHg concns. in fish (killifish and Atlantic silversides). Moreover, MeHg concns. were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concns. were only predictive of concns. of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that det. MeHg input and bioavailability in the water column.
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    Bradley, M. A.; Barst, B. D.; Basu, N. A review of mercury bioavailability in humans and fish. International Journal of Environmental Research and Public Health 2017, 14, 169,  DOI: 10.3390/ijerph14020169
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    A review of mercury bioavailability in humans and fish
    Bradley, Mark A.; Barst, Benjamin D.; Basu, Niladri
    International Journal of Environmental Research and Public Health (2017), 14 (2), 169/1-169/20CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
    To est. human exposure to methylmercury (MeHg), risk assessors often assume 95%-100% bioavailability in their models. However, recent research suggests that assuming all, or most, of the ingested mercury (Hg) is absorbed into systemic circulation may be erroneous. The objective of this paper is to review and discuss the available state of knowledge concerning the assimilation or bioavailability of Hg in fish and humans. In fish, this meant reviewing studies on assimilation efficiency, that is the difference between ingested and excreted Hg over a given period of time. In humans, this meant reviewing studies that mostly investigated bioaccessibility (digestive processes) rather than bioavailability (cumulative digestive + absorptive processes), although studies incorporating absorption for a fuller picture of bioavailability were also included where possible. The outcome of this review shows that in a variety of organisms and exptl. models that Hg bioavailability and assimilation is less than 100%. Specifically, 25 studies on fish were reviewed, and assimilation efficiencies ranged from 10% to 100% for MeHg and from 2% to 51% for Hg(II). For humans, 20 studies were reviewed with bioaccessibility ests. ranging from 2% to 100% for MeHg and 0.2% to 94% for Hg(II). The overall absorption ests. ranged from 12% to 79% for MeHg and 49% to 69% for Hg(II), and were consistently less than 100%. For both fish and humans, a no. of cases are discussed in which factors (e.g., Hg source, cooking methods, nutrients) are shown to affect Hg bioavailability. The summaries presented here challenge a widely-held assumption in the Hg risk assessment field, and the paper discusses possible ways forward for the field.
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    Hall, B. D.; Bodaly, R. A.; Fudge, R. J.; Rudd, J. W. M.; Rosenberg, D. M. Food as the dominant pathway of methylmercury uptake by fish. Water, Air and Soil Pollution 1997, 100, 13– 24,  DOI: 10.1023/A:1018071406537
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    Food as the dominant pathway of methylmercury uptake by fish
    Hall, B. D.; Bodaly, R. A.; Fudge, R. J. P.; Rudd, J. W. M.; Rosenberg, D. M.
    Water, Air, and Soil Pollution (1997), 100 (1-2), 13-24CODEN: WAPLAC; ISSN:0049-6979. (Kluwer Academic Publishers)
    A field expt. was conducted to det. the degree to which fish accumulated methylmercury (MeHg) via their food or via passive uptake from water through the gills. Finescale dace (Phoxinus neogaeus) were held in 2000 L enclosed pens floating in an undisturbed, oligotrophic lake in northwestern Ontario. Fish were exposed to water contg. either low (0.10-0.40 ng L-1), intermediate (0.45-1.30 ng L-1), or high (0.80-2.1 ng L-1) concns. of MeHg. Zooplankton with either low (0.16-0.18 μg g-1 d.w.) or high (0.28-0.76 μg g-1 d.w.) concns. of MeHg were added daily to each pen. Fish fed zooplankton with high concns. of MeHg had significantly higher concns. of mercury in muscle after 32 days than fish fed zooplankton with low concns. of MeHg. Fish feeding on zooplankton with low concns. of MeHg had the same amt. of Hg in their tissues as fish at the start of the expt. Uptake from water was at most 15%. This is the first expt. to confirm that food is the dominant pathway of MeHg bioaccumulation in fish at natural levels of MeHg.
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    Lankov, A.; Ojaveer, H.; Simm, M.; Põllupüü, M.; Möllmann, C. Feeding ecology of pelagic fish species in the Gulf of Riga (Baltic Sea): the importance of changes in the zooplankton community. J. Fish Biol. 2010, 77, 2268– 2284,  DOI: 10.1111/j.1095-8649.2010.02805.x
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    Feeding ecology of pelagic fish species in the Gulf of Riga (Baltic Sea): the importance of changes in the zooplankton community
    Lankov A; Ojaveer H; Simm M; Pollupuu M; Mollmann C
    Journal of fish biology (2010), 77 (10), 2268-84 ISSN:.
    The feeding ecology of four pelagic fish species was studied in relation to their prey availability in the Gulf of Riga (Baltic Sea) during the summer 1999-2006. The zooplankton community was dominated by the cladoceran Bosmina longispina, rotifers Keratella cochlearis and K. quadrata and the copepod Eurytemora affinis, with the highest interannual variability in abundance recorded for B. longispina. The last influenced the diet of adult sprat Sprattus sprattus, juvenile smelt Osmerus eperlanus and three-spined stickleback Gasterosteus aculeatus as these were strongly selecting for B. longispina. The fish feeding activity did not match the abundance dynamics of their preferred prey, suggesting that fishes may switch to consume other prey in case the preferred diet was limited. A considerable dietary overlap indicated high potential competition between pelagic fish species. While herring Clupea harengus membras and G. aculeatus were relying on very different food, the diets of young O. eperlanus and G. aculeatus were very similar. Interannual variability in zooplankton composition and abundance significantly affected the diet composition of fishes, but those changes were insufficient to exert a consistent influence upon fish feeding activity and total amounts of zooplankton consumed.
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    Jacobson, P.; Bengström, U.; Eklöf, J. Size-dependent diet composition and feeding of Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius) in the Baltic Sea. Boreal. Environ. Res. 2019, 24, 137– 153
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    Bergström, U.; Olsson, J.; Casini, M.; Eriksson, B. K.; Fredriksson, R.; Weenhage, H.; Appelberg, M. Stickleback increase in the Baltic Sea - A thorny issue for coastal predatory fish. Estuar Coast Shelf Sci. 2015, 163, 134– 142,  DOI: 10.1016/j.ecss.2015.06.017
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    Griffiths, J. R.; Kadin, M.; Nascimento, F. J. A.; Tamelander, T.; Törnroos, A.; Bonaglia, S.; Bonsdorff, E.; Brüchert, V.; Gårdmark, A.; Järnström, M.; Kotta, J.; Lindegren, M.; Nordström, M. C.; Norkko, A.; Olsson, J.; Weigel, B.; Zydelis, R.; Blenckner, T.; Niiranen, S.; Winder, M. The importance of benthic–pelagic coupling for marine ecosystem functioning in a changing world. Glob. Chang. Biol. 2017, 23, 2179– 2196,  DOI: 10.1111/gcb.13642
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    The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world
    Griffiths Jennifer R; Nascimento Francisco J A; Winder Monika; Kadin Martina; Blenckner Thorsten; Niiranen Susa; Tamelander Tobias; Norkko Alf; Tornroos Anna; Bonsdorff Erik; Jarnstrom Marie; Nordstrom Marie C; Weigel Benjamin; Tornroos Anna; Lindegren Martin; Bonaglia Stefano; Bruchert Volker; Bonaglia Stefano; Gardmark Anna; Olsson Jens; Kotta Jonne; Norkko Alf; Zydelis Ramunas
    Global change biology (2017), 23 (6), 2179-2196 ISSN:.
    Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world.
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    Kiljunen, M.; Peltonen, H.; Lehtiniemi, M.; Uusitalo, L.; Sinisalo, T.; Norkko, J.; Kunnasranta, M.; Torniainen, J.; Rissanen, A. J.; Karjalainen, J. Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs. Limnol Oceanogr 2020, 65, 1706– 1722,  DOI: 10.1002/lno.11413
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    Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs
    Kiljunen, Mikko; Peltonen, Heikki; Lehtiniemi, Maiju; Uusitalo, Laura; Sinisalo, Tuula; Norkko, Joanna; Kunnasranta, Mervi; Torniainen, Jyrki; Rissanen, Antti J.; Karjalainen, Juha
    Limnology and Oceanography (2020), 65 (8), 1706-1722CODEN: LIOCAH; ISSN:0024-3590. (John Wiley & Sons, Inc.)
    Understanding marine ecosystem structure and functioning is crucial in supporting sustainable management of natural resources and monitoring the health of marine ecosystems. The current study utilized stable isotope (SI) mixing models and trophic position models to examine energy flow, trophic relationships, and benthic-pelagic coupling between food web components. Roughly 1900 samples from different trophic levels in the food web, collected during 2001-2010 from four northern and central sub-basins of the Baltic Sea, were analyzed for SI ratios of carbon and nitrogen. Trophic structure of the food webs among the sub-basins was consistent, but there were differences between the proportions of energy in different trophic levels that had originated from the benthic habitat. Mysids and amphipods served as important links between the benthic and pelagic ecosystems. Much (35-65%) of their energy originated from the benthic zone but was transferred to higher trophic levels in the pelagic food web by consumption by herring (Clupea harengus). One percent to twenty-four percent of the energy consumption of apex seal predators (Halichoerus grypus and Pusa hispida) and predatory fish (Salmo salar) was derived from benthic zone. Diets of mysids and amphipods differed, although some overlap in their dietary niches was obsd. The food web in the Gulf of Finland was more influenced by the benthic subsystem than food webs in the other sub-basins. The baseline levels of δ13C and δ15N differed between sub-basins of the Baltic Sea, indicating differences in the input of org. matter and nutrients to each sub-basin.
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    Won, E. J.; Choi, B.; Hong, S.; Khim, J. S.; Shin, K. H. Importance of accurate trophic level determination by nitrogen isotope of amino acids for trophic magnification studies: A review. Environ. Pollut. 2018, 238, 677– 690,  DOI: 10.1016/j.envpol.2018.03.045
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    Importance of accurate trophic level determination by nitrogen isotope of amino acids for trophic magnification studies: A review
    Won, Eun-Ji; Choi, Bohyung; Hong, Seongjin; Khim, Jong Seong; Shin, Kyung-Hoon
    Environmental Pollution (Oxford, United Kingdom) (2018), 238 (), 677-690CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)
    During the last several decades, persistent org. pollutants and metals cause great concern for their toxicity in organisms as well as for their bioaccumulation and/or trophic transfer through the food chains in ecosystems. A large no. of studies therefore have focused on the trophic levels of organisms to illustrate food web structure, as a crit. component in the study of pollutant dynamics and biomagnification. The trends in biomagnification of pollutants in food webs indeed provide fundamental information about the properties and fates of pollutants in ecosystems. The trophic magnification supports the establishment of a reliable trophic structure, which can further aid the understanding of the transport and exposure routes of contaminants in accumulation and risk assessments. Recently, efforts to interpret the food web structure using carbon and nitrogen stable isotope ratios have contributed to better understanding of the fate of pollutants in the ecosystem. However, it is known that this isotope anal. of bulk ones has many weaknesses, particularly for uncertainties on the est. of trophic levels and therefore of magnification factors for studied organisms, enough to support a regulatory interpretation. In this review, we collate studies that investigated biomagnification characteristics of pollutants in aquatic ecosystems, along with calcd. trophic magnification factors. Moreover, we introduce a novel approach, compd.-specific stable isotope anal. of nitrogen in amino acids, to establish reliable food web structures and accurate trophic levels for biomagnification studies. This method promises to provide sound results for interpreting the influence of the pollutant in organisms, along with their bioaccumulation and magnification characteristics, as well as that in ecosystem.
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    Elliott, H.; Braune, B. M.; Elliott, J. E. Beyond bulk δ15N: Combining a suite of stable isotopic measures improves the resolution of the food webs mediating contaminant signals across space, time and communities. Environ. Int. 2021, 148, 106370,  DOI: 10.1016/j.envint.2020.106370
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    Beyond bulk d15N: Combining a suite of stable isotopic measures improves the resolution of the food webs mediating contaminant signals across space, time and communities
    Elliott, Kyle H.; Braune, Birgit M.; Elliott, John E.
    Environment International (2021), 148 (), 106370CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
    Top predators are used as indicators of contaminant trends across space and time. However, signals are integrated over complex food webs, and variation in diet may confound such signals. Trophic position, assessed by bulk δ15N, is widely used to infer the variation in diet relevant to contamination, yet a single variable cannot completely describe complex food webs. Thus, we examd. relationships across three aquatic systems varying from a single species to a small food web using bulk values from four isotopes and 21 amino acid-specific values. Because variation in baseline ('source') δ15N can confound ests. of trophic position , we calcd. trophic position from the difference between δ15Ntrophic (δ15N for amino acids that change with trophic position) and δ15Nsource (δ15N for amino acids that do not change with trophic position). Across all three systems, variation in δ15Nsource explained over half of the variation in bulk δ15N, and stable isotope values that reflected the base of the food web (δ13C, δ18O, δ34S) predicted contaminants as well or better than δ15N-which was supported by a meta-anal. of other studies. In ospreys feeding in lakes, variation in δ15Nsource across space created a spurious relationship between ΣDDT and apparent trophic position, and masked a relationship between ΣPCB and trophic position. In a seabird guild, changes in diet over time obscured temporal variation in contaminants over five decades. In Arctic fish and invertebrates, more accurate trophic magnification factors were calcd. using δ15Ntrophic-source. Thus, (1) using δ15Ntrophic-source, instead of bulk δ15N, avoided incorrect conclusions and improved accuracy of trophic magnification factors necessary to assess risk to top predators; and (2) diet assessed with multiple spatial isotopes, rather than δ15N alone, was essential to understand patterns in contaminants across space, time and biol. communities. Trophic position was most important for lipophilic 'legacy' contaminants (ΣDDT, ΣPCB) and habitat was most important for other contaminants (ΣPBDE, ΣPFAS, mercury). We argue that the use of amino acid-specific anal. of δ15N alongside 'non-trophic' isotopes should be a core feature of any study that examines the influence of trophic position on chem. pollution, as required for a chem. to be added to international conventions such as the Stockholm Convention.
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    Isomursu, M.; Koivusaari, J.; Stjernberg, T.; Hirvelä-Koski, V.; Venäläinen, E.-R. Lead poisoning and other human-related factors cause significant mortality in white-tailed eagles. Ambio 2018, 1– 11
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    Borgå, K.; Fisk, A. T.; Hoekstra, P. F.; Muir, D. C. G. Biological and chemical factors of importance in the bioaccumulation and trophic transfer of persistent organochlorine contaminants in arctic marine food webs. Environ. Toxicol. Chem. 2004, 23, 2367– 2385,  DOI: 10.1897/03-518
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    Biological and chemical factors of importance in the bioaccumulation and trophic transfer of persistent organochlorine contaminants in Arctic marine food webs
    Borga, Katrine; Fisk, Aaron T.; Hoekstra, Paul F.; Muir, Derek C. G.
    Environmental Toxicology and Chemistry (2004), 23 (10), 2367-2385CODEN: ETOCDK; ISSN:0730-7268. (SETAC Press)
    A review is given. Recent studies of arctic marine food webs have provided detailed insights regarding the biol. and chem. factors that influence the bioaccumulation and trophic transfer of persistent organochlorine (OC) contaminants in aquatic systems. This paper summarizes the recent literature with an emphasis on identifying important ecol. factors for explaining variability of OC concns. among organisms. The Arctic ecosystem has a no. of unique attributes, including long food chains, reduced diversity of species, similar food webs across the entire region, and limited influence from pollution point sources. Lipid content, body size, age, gender, reprodn., habitat use, migration, biotransformation, seasonal changes in habitat conditions, feeding ecol., and trophic position have all been demonstrated to influence OC concns. and bioaccumulation in arctic marine biota. The relative importance of each factor varies among OCs and organisms. Diet or trophic level is the dominant factor influencing OC concns. and dynamics in seabirds and marine mammals, although biotransformation can significantly influence nonrecalcitrant OCs, such as hexachlorocyclohexane isomers. Dietary accumulation of OCs is also an important route of exposure for arctic fish and zooplankton, and biomagnification of OCs may also occur among these organisms. To date, only limited attempts have been made to model trophic transfer of OCs in the arctic marine food web. Although models developed to assess OC dynamics in aquatic food webs have included some biol. variables (e.g., lipid content, feeding rate, diet compn., and growth rate), selection of processes included in these models as well as their math. solns. and parameterization all introduce simplification. This reduces biol. validity of the models and may be particularly problematic in a highly seasonal environment, such as the Arctic Ocean.
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    Gobas, F. A.P.C.; de Wolf, W.; Burkhard, L. P.; Verbruggen, E.; Plotzke, K. Revisiting bioaccumulation criteria for POPs and PBT assessments. Integ Environ. Assess Manag 2009, 5, 624– 637,  DOI: 10.1897/IEAM_2008-089.1
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    Revisiting bioaccumulation criteria for POPs and PBT assessments
    Gobas, Frank A. P. C.; de Wolf, Watze; Burkhard, Lawrence P.; Verbruggen, Eric; Plotzke, Kathleen
    Integrated Environmental Assessment and Management (2009), 5 (4), 624-637CODEN: IEAMCK; ISSN:1551-3777. (Society of Environmental Toxicology and Chemistry)
    A review. Scientists from academia, industry, and government reviewed current international regulations for the screening of com. chems. for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for "bioaccumulative substances," improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calcg. bioaccumulation properties, and a framework for screening com. chems. for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.
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    Dietz, R.; Fort, J.; Sonne, C.; Albert, C.; Bustnes, J. O.; Christensen, T. K.; Ciesielski, T. M.; Danielsen, J.; Dastnai, S.; Eens, M.; Erikstad, K. E.; Galatius, A.; Garbus, S. E.; Gilg, O.; Hanssen, S. E.; Helander, B.; Helberg, M.; Jaspers, V. L. B.; Jenssen, B. M.; Jonsson, J. E.; Kauhala, K.; Kolbeinsson, Y.; Kyhn, L. A.; Labansen, A. L.; Larsen, M. M.; Linstrøm, U.; Reiertsen, T. K.; Rigét, F. F.; Roos, A.; Strand, J.; Strøm, H.; Sveegaard, S.; Søndergaard, J.; Sun, J.; Teilmann, J.; Therkildsen, O. R.; Thórarinsson, T. L.; Tjørnløv, R. S.; Wilson, S.; Eulaers, I. A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves. Environ. Int. 2021, 146, 106178,  DOI: 10.1016/j.envint.2020.106178
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    A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves
    Dietz, Rune; Fort, Jerome; Sonne, Christian; Albert, Celine; Bustnes, Jan Ove; Christensen, Thomas Kjaer; Ciesielski, Tomasz Maciej; Danielsen, Johannis; Dastnai, Sam; Eens, Marcel; Erikstad, Kjell Einar; Galatius, Anders; Garbus, Svend-Erik; Gilg, Olivier; Hanssen, Sveinn Are; Helander, Bjorn; Helberg, Morten; Jaspers, Veerle L. B.; Jenssen, Bjoern Munro; Jonsson, Jon Einar; Kauhala, Kaarina; Kolbeinsson, Yann; Kyhn, Line Anker; Labansen, Aili Lage; Larsen, Martin Moerk; Lindstoem, Ulf; Reiertsen, Tone K.; Riget, Frank F.; Roos, Anna; Strand, Jakob; Stroem, Hallvard; Sveegaard, Signe; Soendergaard, Jens; Sun, Jiachen; Teilmann, Jonas; Therkildsen, Ole Roland; Thorarinsson, Thorkell Lindberg; Tjoernloev, Rune Skjold; Wilson, Simon; Eulaers, Igor
    Environment International (2021), 146 (), 106178CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
    A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geog. focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concns. within the High Risk Category (HRC) and Severe Risk Category (SRC). The corresponding percentages for seabirds, fish and bivalves were 2.7%, 25% and 8.0%, resp., although fish and bivalves were not represented in the SRC. Juveniles from all species showed to be at no or low risk. In comparison to the same species in the adjacent waters, i.e. the Greater North Sea and the North Atlantic, the estd. risk for Baltic populations is not considerably higher. These findings suggest that over the past few decades the Baltic Sea has improved considerably with respect to presenting Hg exposure to its local species, while it does still carry a legacy of elevated Hg levels resulting from high neighboring industrial and agricultural activity and slow water turnover regime.
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  1. Kang Luo, Wei Yuan, Zhiyun Lu, Zichun Xiong, Che-Jen Lin, Xun Wang, Xinbin Feng. Unveiling the Sources and Transfer of Mercury in Forest Bird Food Chains Using Techniques of Vivo-Nest Video Recording and Stable Isotopes. Environmental Science & Technology 2024, 58 (13) , 6007-6018. https://doi.org/10.1021/acs.est.3c10972
  2. Xiaobo Zheng, Xiaodan Wu, Ruifeng Lu, Xingpei Cao, Bi-Xian Mai. Identification of Species-Specific Prey Uptake and Biotransformation of Chiral Polychlorinated Biphenyls (PCBs) in Riparian and Aquatic Food Webs. Environmental Science & Technology 2023, 57 (48) , 20282-20291. https://doi.org/10.1021/acs.est.3c07377
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Cite this: Environ. Sci. Technol. 2022, 56, 16, 11440–11448
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https://doi.org/10.1021/acs.est.2c03846
Published August 3, 2022

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  • Abstract

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    Figure 1

    Figure 1. Map of the sampling locations.

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    Figure 2

    Figure 2. Linear regressions between log10[THg dw] (μg g–1) and trophic position for (A) benthic habitat (all species), (B) benthic habitat (no birds), (C) pelagic habitat (all species), and (D) pelagic habitat (no birds). The solid lines are for regression of the one-source model (eqs 1 and 3), while the dashed lines are for the two-source model (eqs 2 and 4).

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    Figure 3

    Figure 3. Heatmap of biomagnification factors (BMFs) for relevant predator–prey pairs (A) normalized for TP (eq 6) or (B) not (eq 7). Negative BMF values were removed.

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  • References

    This article references 43 other publications.

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      Trophic magnification factors: Considerations of ecology, ecosystems, and study design
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      Integrated Environmental Assessment and Management (2012), 8 (1), 64-84CODEN: IEAMCK; ISSN:1551-3777. (John Wiley & Sons Inc.)
      A review. Recent reviews by researchers from academia, industry, and government have revealed that the criteria used by the Stockholm Convention on persistent org. pollutants under the United Nations Environment Program are not always able to identify the actual bioaccumulative capacity of some substances, by use of chem. properties such as the octanol-water partitioning coeff. Trophic magnification factors (TMFs) were suggested as a more reliable tool for bioaccumulation assessment of chems. that have been in commerce long enough to be quant. measured in environmental samples. TMFs are increasingly used to quantify biomagnification and represent the av. diet-to-consumer transfer of a chem. through food webs. They differ from biomagnification factors, which apply to individual species and can be highly variable between predator-prey combinations. The TMF is calcd. from the slope of a regression between the chem. concn. and trophic level of organisms in the food web. The trophic level can be detd. from stable N isotope ratios (δ15N). In this article, we give the background for the development of TMFs, identify and discuss impacts of ecosystem and ecol. variables on their values, and discuss challenges and uncertainties assocd. with contaminant measurements and the use of δ15N for trophic level estns. Recommendations are provided for exptl. design, data treatment, and statistical analyses, including advice for users on reporting and interpreting TMF data. Interspecies intrinsic ecol. and organismal properties such as thermoregulation, reproductive status, migration, and age, particularly among species at higher trophic levels with high contaminant concns., can influence the TMF (i.e., regression slope). Following recommendations herein for study design, empirical TMFs are likely to be useful for understanding the food web biomagnification potential of chems., where the target is to definitively identify if chems. biomagnify (i.e., TMF > or < 1). TMFs may be less useful in species- and site-specific risk assessments, where the goal is to predict abs. contaminant concns. in organisms in relation to threshold levels.
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      Modeling food chain structure and contaminant bioaccumulation using stable nitrogen isotopes
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      A review with 28 refs. on food chain structure in predatory fish models. The nitrogen pools of animals are enriched in 15N relative to their food, with the top predators having the highest concns. of this stable isotope. The use of δ15N to indicate trophic position depends on the degree to which it reflects variation in the underlying food-web structure, rather than variable fractionation along the food chain. Here we compare adult lake trout, a top pelagic predator, from a series of lakes, and find that δ15N values vary from 7.5 to 17.5‰, a surprisingly wide range for one species. The length of the food chain can explain this variation, supporting the idea that δ15N is a food-web descriptor. Food-chain length was measured by the presence or absence of two intermediate trophic levels, pelagic forage fish and the macrozooplankter, Mysis relicta, each of which when present contributes about three δ15N units to the trout signature. We find that δ15 N can be used as a continuous, integrative measure of trophic position, which is supported by its correlation to mercury levels in lake trout.
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      Van den Brink, P. J.; Baird, D. J.; Baveco, H. J. M.; Focks, A. The use of traits based approaches and eco(toxico)logical models to advance ecological risk assessment framework for chemicals. Integr Environ. Assess Manag 2013, 9, e47– e57,  DOI: 10.1002/ieam.1443
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      The use of traits-based approaches and eco(toxico)logical models to advance the ecological risk assessment framework for chemicals
      Van den Brink, Paul J.; Baird, Donald J.; Baveco, Hans; Focks, Andreas
      Integrated Environmental Assessment and Management (2013), 9 (3), e47-e57CODEN: IEAMCK; ISSN:1551-3777. (John Wiley & Sons Inc.)
      A review. This article presents a framework to diagnose and predict the effects of chems., integrating 2 promising tools to incorporate more ecol. into ecol. risk assessment, namely traits-based approaches and ecol. modeling. Traits-based approaches are used increasingly to derive correlations between the occurrence of species traits and chem. exposure from biol. and chem. monitoring data. This assessment can also be used in a diagnostic way, i.e., to identify the chems. probably posing the highest risks to the aquatic ecosystems. The article also describes how ecol. models can be used to explore how traits govern the species-substance interactions and to predict effects at the individual, population, and community and ecosystem level, i.e., from the receptor to the landscape level. This can be done by developing models describing the toxicokinetics and toxicodynamics of the chem. in the individual, the life-history of species and the connectivity of populations, detg. their recovery, and the food web relations at the community and ecosystem level that det. the indirect effects. Special attention is given on how spatial aspects can be included in the ecol. risk assessments using ecol. models. The components of the framework are introduced and critically discussed. We describe how the different tools and data generated through experimentation (lab. and semifield) and biomonitoring can be integrated. The article uses examples from the aquatic compartment, but the concepts that are used, and their integration within the framework, can be generalized to other environmental compartments. Integr Environ Assess Manag 2013;9:e47-e57. © 2013 SETAC.
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      Lavoie, R. A.; Hebert, C. E.; Rail, J. F.; Braune, B. M.; Yumvihoze, E.; Hill, L. G.; Lean, D. R. S. Trophic structure and mercury distribution in a Gulf of St. Lawrence (Canada) food web using stable isotope analysis. Sci. Total Environ. 2010, 408, 5529– 5539,  DOI: 10.1016/j.scitotenv.2010.07.053
      4
      Trophic structure and mercury distribution in a Gulf of St. Lawrence (Canada) food web using stable isotope analysis
      Lavoie, Raphael A.; Hebert, Craig E.; Rail, Jean-Francois; Braune, Birgit M.; Yumvihoze, Emmanuel; Hill, Laura G.; Lean, David R. S.
      Science of the Total Environment (2010), 408 (22), 5529-5539CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Even at low concns. in the environment, mercury has the potential to biomagnify in food chains and reaches levels of concern in apex predators. The aim was to relate the transfer of total Hg (THg) and methylmercury (MeHg) in a Gulf of St. Lawrence food web to the trophic structure, from primary consumers to seabirds, using δ15N and δ13C isotope anal. and phys. environmental parameters. The energy reaching upper trophic level species was principally derived from pelagic primary prodn., with particulate org. matter (POM) at the base of the food chain. We developed a biomagnification factor (BMF) taking into account the various prey items consumed by a given predator using stable isotope mixing models. This BMF provides a more realistic estn. than when using a single prey. Lipid content, body wt., trophic level and benthic connection explained 77.4 and 80.7% of the variation in THg and MeHg concns., resp., in this food web. When other values were held const., relations with lipid and benthic connection were neg. whereas relations with trophic level and body wt. were pos. THg and MeHg biomagnified in this food web with biomagnification power values (slope of the relation with δ15N) of 0.170 and 0.235, resp., on wet wt. and 0.134 and 0.201, resp., on dry wt. Values of biomagnification power were greater for pelagic and benthopelagic species compared to benthic species whereas the opposite trend was obsd. for levels at the base of the food chain. This suggests that Hg would be readily bioavailable to organisms at the base of the benthic food chain, but trophic transfer would be more efficient in each trophic level of pelagic and benthopelagic food chains.
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      Chen, C. Y.; Borsuk, M. E.; Bugge, D. M.; Hollweg, T.; Balcom, P. H.; Ward, D. M.; Williams, J.; Mason, R. P. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the Northeast United States. PLoS One 2014, 9, e89305,  DOI: 10.1371/journal.pone.0089305
      5
      Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the Northeast United States
      Chen, Celia Y.; Borsuk, Mark E.; Bugge, Deenie M.; Hollweg, Terill; Balcom, Prentiss H.; Ward, Darren M.; Williams, Jason; Mason, Robert P.
      PLoS One (2014), 9 (2), e89305/1-e89305/11, 11 pp.CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
      Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concns. in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concns. in water column particulate material, but not in sediments, were predictive of MeHg concns. in fish (killifish and Atlantic silversides). Moreover, MeHg concns. were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concns. were only predictive of concns. of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that det. MeHg input and bioavailability in the water column.
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      Muto, E. Y.; Soares, L. S. H.; Sarkis, J. E. S.; Hortellani, M. A.; Petti, M. A. V.; Corbisier, T. N. Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil. Mar. Ecol.: Prog. Ser. 2014, 512, 55– 69,  DOI: 10.3354/meps10892
      6
      Biomagnification of mercury through the food web of the Santos continental shelf, subtropical Brazil
      Muto, Elizabeti Y.; Soares, Lucy S. H.; Sarkis, Jorge E. S.; Hortellani, Marcos A.; Petti, Monica A. V.; Corbisier, Thais N.
      Marine Ecology: Progress Series (2014), 512 (), 55-69, 15 pp.CODEN: MESEDT; ISSN:0171-8630. (Inter-Research)
      This study was conducted on the continental shelf surrounding a large metropolitan region on the coast of S~ao Paulo State, Southeast Brazil. This region harbours a large industrial plant and the largest port in Latin America, both of which release pollutants into the Santos-S~ao Vicente estuarine system. High levels of Hg have been reported in sediments and fish from the estuaries and Santos Bay; however, data for the biota in offshore waters are scarce, and the biomagnification of Hg across the food web here has never been assessed. In this study, the trophic structure of the Santos shelf was addressed through the carbon and nitrogen stable isotope compns. of different species across a trophic gradient. We detd. the total Hg levels (THg, dry wt.) of invertebrates and fish to est. the rate of biomagnification of this metal in the benthic and pelagic food webs. The lowest mean THg levels were found in zooplankton (0.006 μg g-1) and surface-depositivore polychaetes (0.011 μg g-1); the highest THg levels were found in the largest fishes: Patagonian flounder (0.825 μg g-1), fat snook (0.714 μg g-1), and lesser guitarfish (0.639 μg g-1). Overall, the Hg concn. in fish was below the recommended limit for human consumption. The THg and δ15N were pos. correlated in both food webs; however, the rate of biomagnification was higher and the basal Hg was lower in the pelagic food web. These differences may be related to the differing bioavailability of mercury in water and sediment, the higher diversity of prey and more complex feeding interactions in the benthic food web, and metabolic differences among different taxa.
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    7. 7
      Ciesielski, T. M.; Pastukhov, M. V.; Leeves, S. A.; Farkas, J.; Lierhagen, S.; Poletaeva, V. I.; Jenssen, B. M. Differential bioaccumulation of potentially toxic elements in benthic and pelagic food chains in Lake Baikal. Environ. Sci. Pollut Res. 2016, 23, 15593– 15604,  DOI: 10.1007/s11356-016-6634-0
      7
      Differential bioaccumulation of potentially toxic elements in benthic and pelagic food chains in Lake Baikal
      Ciesielski, Tomasz M.; Pastukhov, Mikhail V.; Leeves, Sara A.; Farkas, Julia; Lierhagen, Syverin; Poletaeva, Vera I.; Jenssen, Bjoern M.
      Environmental Science and Pollution Research (2016), 23 (15), 15593-15604CODEN: ESPLEC; ISSN:0944-1344. (Springer)
      Lake Baikal is located in eastern Siberia in the center of a vast mountain region. Even though the lake is regarded as a unique and pristine ecosystem, there are existing sources of anthropogenic pollution to the lake. In this study, the concns. of the potentially toxic trace elements As, Cd, Pb, Hg, and Se were analyzed in water, plankton, invertebrates, and fish from riverine and pelagic influenced sites in Lake Baikal. Concns. of Cd, Hg, Pb and Se in Lake Baikal water and biota were low, while concns. of As were similar or slightly higher compared to in other freshwater ecosystems. The bioaccumulation potential of the trace elements in both the pelagic and the benthic ecosystems differed between the Selenga Shallows (riverine influence) and the Listvenichnyi Bay (pelagic influence). Despite the one order of magnitude higher water concns. of Pb in the Selenga Shallows, Pb concns. were significantly higher in both pelagic and benthic fish from the Listvenichnyi Bay. A similar trend was obsd. for Cd, Hg, and Se. The identified enhanced bioavailability of contaminants in the pelagic influenced Listvenichnyi Bay may be attributed to a lower abundance of natural ligands for contaminant complexation. Hg was found to biomagnify in both benthic and pelagic Baikal food chains, while As, Cd, and Pb were biodiluted. At both locations, Hg concns. were around seven times higher in benthic than in pelagic fish, while pelagic fish had two times higher As concns. compared to benthic fish. The calcd. Se/Hg molar ratios revealed that, even though Lake Baikal is located in a Se-deficient region, Se is still present in excess over Hg and therefore the probability of Hg induced toxicity in the endemic fish species of Lake Baikal is assumed to be low.
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    8. 8
      Fan, S.; Wang, B.; Liu, H.; Gao, S.; Li, T.; Wang, S.; Liu, Y.; Liu, X.; Wan, Y. Trophodynamics of organic pollutants in pelagic and benthic food webs of Lake Dianchi: Importance of ingested sediment as uptake route. Environ. Sci. Technol. 2017, 51, 14135– 14143,  DOI: 10.1021/acs.est.7b03681
      8
      Trophodynamics of Organic Pollutants in Pelagic and Benthic Food Webs of Lake Dianchi: Importance of Ingested Sediment As Uptake Route
      Fan, Senrong; Wang, Beili; Liu, Hang; Gao, Shixiong; Li, Tong; Wang, Shuran; Liu, Yong; Liu, Xueqin; Wan, Yi
      Environmental Science & Technology (2017), 51 (24), 14135-14143CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Habitat is of great importance in detg. the trophic transfer of pollutants in freshwater ecosystems; however, the major factors influencing chem. trophodynamics in pelagic and benthic food webs remain unclear. This study investigated the levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), polycyclic arom. hydrocarbons (PAHs), and substituted PAHs (s-PAHs) in 2 plankton species, 6 invertebrate species, and 10 fish species collected from Lake Dianchi in southern China. Relatively high concns. of PAHs and s-PAHs were detected with total concns. of 11.4-1400 ng/g wet wt. (ww) and 5.3-115 ng/g ww, resp. Stable isotope anal. and stomach content anal. were applied to quant. det. the trophic level of individual organisms and discriminate between pelagic and benthic pathways, and the trophodynamics of the detected compds. in the two food webs were assessed. P,p'-DDE was found to exhibit relatively higher trophic magnification rate in the pelagic food web than in the benthic food web. In contrast, PAHs and s-PAHs exhibited greater diln. rates along the trophic levels in the pelagic food web. The lower species differences of pollutants accumulated in benthic organisms compared to pelagic organisms is attributable to extra uptake via ingested sediment in benthos. The av. uptake proportions of PAHs and s-PAHs via ingested sediment in benthic biotas were estd. to be 31-77%, and that of p,p'-DDE was 46%. The uptake routes are of importance for assessing the trophic magnification potentials of org. pollutants, esp. in eutrophic freshwater ecosystems.
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    9. 9
      Hop, H.; Borga, K.; Gabrielsen, G. W.; Kleivane, L.; Skaare, J. U. Food web magnification of persistent organic pollutants in poikilotherms and homeotherms from the Barents Sea. Environ. Sci. Technol. 2002, 36, 2589– 2597,  DOI: 10.1021/es010231l
      9
      Food Web Magnification of Persistent Organic Pollutants in Poikilotherms and Homeotherms from the Barents Sea
      Hop, Haakon; Borgaa, Katrine; Gabrielsen, Geir Wing; Kleivane, Lars; Skaare, Janneche Utne
      Environmental Science and Technology (2002), 36 (12), 2589-2597CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Food web magnification of persistent org. pollutants (POPs) was detd. for the Barents Sea food web using δ15N as a continuous variable for assessing trophic levels (TL). The food web investigated comprised zooplankton, ice fauna and fish (poikilotherms, TL 1.7-3.3), and seabirds and seals (homeotherms, TL 3.3-4.2), with zooplankton representing the lowest and glaucous gull the highest trophic level. Concns. of lipophilic and persistent organochlorines were orders of magnitude higher in homeotherms than in poikilotherms. These compds. had significantly higher rates of increase per trophic level in homeotherms relative to poikilotherms, with the highest food web magnification factors (FWMFs) for cis-chlordane and p,p'-DDE. Some compds., such as trans-nonachlor and HCB, had similar rates of increase throughout the food web, whereas compds. that are more readily eliminated (γ-HCH) showed no relationship with trophic level. It is preferable to calc. FWMFs with regard to thermal groups, because the different energy requirements and biotransformation abilities between poikilotherms and homeotherms may give different rates of contaminant increase with trophic level. When biomagnification is compared between ecosystems, FWMFs are preferable to single predator-prey biomagnification factors. FWMFs represent a trophic level increase of contaminants that is av. for the food chain rather than an increase for a specific predator-prey relationship. The Barents Sea FWMFs were generally comparable to those detd. for marine food webs with similar food chain lengths in the Canadian Arctic.
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    10. 10
      Wang, J.; Newman, M. C.; Xu, X.; Liang, L. Higher and more variable methylmercury biomagnification factors for floodplain than the contiguous river (South River, Virginia USA). Ecotoxicol. Environ. Saf. 2013, 92, 191– 198,  DOI: 10.1016/j.ecoenv.2012.04.023
      10
      Higher and more variable methylmercury biomagnification factors for floodplain than the contiguous river (South River, Virginia USA)
      Wang, Jincheng; Newman, Michael C.; Xu, Xiaoyu; Liang, Lian
      Ecotoxicology and Environmental Safety (2013), 92 (), 191-198CODEN: EESADV; ISSN:0147-6513. (Elsevier B.V.)
      Extending previous trophic transfer studies of the mercury-contaminated South River watershed, predictive models were built for mercury biomagnification in floodplain food webs at two more locations (North Park and Grand Cavern). Four of five models built to date based on methylmercury and δ15N met the a priori requirement for useful prediction (prediction r2≈0.80). An addnl. factor included in models was organism thermoregulatory strategy (poikilothermy or homeothermy). The methylmercury food web biomagnification factors (FWMFs, fold increase per trophic level) for the North Park and Grand Cavern locations were 17.4 (95% CI of 9.5-31.6) and 6.2 (95% CI of 3.5-11.0) resp. FWMF calcd. in 2009 were 9.3 (95% CI of 5.4-16.2) for the Augusta Forestry Center and 25.1 (95% CI of 12.6-50.1) for Grottoes Town Park. The overall South River floodplain FWMF generated by meta-anal. of the four locations was 12.4 (95% CI of 6.8-22.3). These results supported previous findings that the South River floodplain food webs had higher biomagnification factors than the contiguous aquatic food web (4.6, 95% CI of 3.6-5.7). Floodplain FWMFs were also more variable than those of the river.
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    11. 11
      Romero-Romero, S.; Herrero, L.; Fernandez, M.; Gomara, B.; Acuna, J. L. Biomagnification of persistent organic pollutants in a deep-sea, temperate food web. Sci. Total Environ. 2017, 605–606, 589– 597,  DOI: 10.1016/j.scitotenv.2017.06.148
      11
      Biomagnification of persistent organic pollutants in a deep-sea, temperate food web
      Romero-Romero, Sonia; Herrero, Laura; Fernandez, Mario; Gomara, Belen; Acuna, Jose Luis
      Science of the Total Environment (2017), 605-606 (), 589-597CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Polychlorinated biphenyls (PCBs), polybrominated di-Ph ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were measured in a temperate, deep-sea ecosystem, the Avile´s submarine Canyon (AC; Cantabrian Sea, Southern Bay of Biscay). There was an increase of contaminant concn. with the trophic level of the organisms, as calcd. from stable nitrogen isotope data (δ15N). Such biomagnification was only significant for the pelagic food web and its magnitude was highly dependent on the type of top predators included in the anal. The trophic magnification factor (TMF) for PCB-153 in the pelagic food web (spanning four trophic levels) was 6.2 or 2.2, depending on whether homeotherm top predators (cetaceans and seabirds) were included or not in the anal., resp. Since body size is significantly correlated with δ15N, it can be used as a proxy to est. trophic magnification, what can potentially lead to a simple and convenient method to calc. the TMF. In spite of their lower biomagnification, deep-sea fishes showed higher concns. than their shallower counterparts, although those differences were not significant. In summary, the AC fauna exhibits contaminant levels comparable or lower than those reported in other systems.
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    12. 12
      Franklin, J. How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances. Integr. Environ. Assess. Manag. 2016, 12, 6– 20,  DOI: 10.1002/ieam.1642
      12
      How reliable are field-derived biomagnification factors and trophic magnification factors as indicators of bioaccumulation potential? Conclusions from a case study on per- and polyfluoroalkyl substances
      Franklin, James
      Integrated Environmental Assessment and Management (2016), 12 (1), 6-20CODEN: IEAMCK; ISSN:1551-3777. (John Wiley & Sons Inc.)
      This review examines the usefulness of the metrics BMF (biomagnification factor) and TMF (trophic magnification factor), derived from field measurements of the levels of contaminants in naturally occurring biota, for characterizing the bioaccumulation potential ("B") of chems. Trophic magnification factor and BMF values greater than 1.0 are often considered to be the most conclusive indicators of B status, and the TMF criterion has been referred to as the "gold std." for B categorization. Although not wishing to dispute the theor. primacy of field-derived BMFs and TMFs as B metrics, we make the case that, in practice, the study-to-study (and even within-study) variability of the results is so great that they are of very restricted usefulness for assessing B status, at least in the case of the per- and polyfluoroalkyl substances (PFASs), on which we focus here. This conclusion is based on an anal. of the results of 24 peer-reviewed studies reporting field-derived BMFs or TMFs for 14 PFASs, for which BMF values often range over several orders of magnitude from <<1.0 to >>1.0, sometimes even in the same study. For TMFs, the range is a factor of approx. 20 for the most intensely studied PFASs (perfluorooctanoic acid [PFOA] and perfluorooctanesulfonic acid [PFOS]). We analyze the possible causes for such variability: To some extent it results from the differing ways in which the metrics are expressed, but most of the scatter is likely attributable to such factors as nonachievement of the tacitly assumed steady-state conditions, uncertainties in the feeding ecol., the impact of metab. of precursor compds., and so forth. As more trustworthy alternatives to field-derived BMFs and TMFs, we suggest the implementation of dietary BMF studies performed under strictly controlled conditions on aquatic, terrestrial, and avian species, as well as the consideration of measured elimination half-lives, which have been demonstrated to be directly related to BMF values. Integr Environ Assess Manag 2016;12:6-20. © 2015 The Author. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.
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    13. 13
      Reusch, T. B. H.; Dierking, J.; Andersson, H. C.; Bonsdorff, E.; Carstensen, J.; Casini, M.; Czajkowski, M.; Hasler, B.; Hinsby, K.; Hyytiäinen, K.; Johannesson, K.; Jomaa, S.; Jormalainen, V.; Kuosa, H.; Kurland, S.; Laikre, L.; MacKenzie, B. R.; Margonski, P.; Melzner, F.; Oesterwind, D.; Ojaveer, H.; Refsgaard, J. C.; Sandström, A.; Schwarz, G.; Tonderski, K.; Winder, M.; Zandersen, M. The Baltic Sea as a time machine for the future coastal ocean. Sci. Adv. 2018, 4, 8195,  DOI: 10.1126/sciadv.aar8195
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      The Baltic Sea as a time machine for the future coastal ocean
      Reusch, Thorsten B. H.; Dierking, Jan; Andersson, Helen C.; Bonsdorff, Erik; Carstensen, Jacob; Casini, Michele; Czajkowski, Mikolaj; Hasler, Berit; Hinsby, Klaus; Hyytiaeinen, Kari; Johannesson, Kerstin; Jomaa, Seifeddine; Jormalainen, Veijo; Kuosa, Harri; Kurland, Sara; Laikre, Linda; Mackenzie, Brian R.; Margonski, Piotr; Melzner, Frank; Oesterwind, Daniel; Ojaveer, Henn; Refsgaard, Jens Christian; Sandstroem, Annica; Schwarz, Gerald; Tonderski, Karin; Winder, Monika; Zandersen, Marianne
      Science Advances (2018), 4 (5), eaar8195/1-eaar8195/16CODEN: SACDAF; ISSN:2375-2548. (American Association for the Advancement of Science)
      Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, uncertain projections, and a lack of test cases for management. We argue that the Baltic Sea can serve as a time machine to study consequences and mitigation of future coastal perturbations, due to its unique combination of an early history of multistressor disturbance and ecosystem deterioration and early implementation of crossborder environmental management to address these problems. The Baltic Sea also stands out in providing a strong scientific foundation and accessibility to long-term data series that provide a unique opportunity to assess the efficacy of management actions to address the breakdown of ecosystem functions. Trend reversals such as the return of top predators, recovering fish stocks, and reduced input of nutrient and harmful substances could be achieved only by implementing an international, cooperative governance structure transcending its complex multistate policy setting, with integrated management of watershed and sea. The Baltic Sea also demonstrates how rapidly progressing global pressures, particularly warming of Baltic waters and the surrounding catchment area, can offset the efficacy of current management approaches. This situation calls for management that is (i) conservative to provide a buffer against regionally unmanageable global perturbations, (ii) adaptive to react to newmanagement challenges, and, ultimately, (iii) multisectorial and integrative to address conflicts assocd. with economic trade-offs.
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    14. 14
      HELCOM Thematic Assessment of Hazardous Substances 2011–2016; Baltic Marine Environment Protection Commission, 2018; p 157.
      There is no corresponding record for this reference.
    15. 15
      de Wit, C. A.; Bossi, R.; Dietz, R.; Dreyer, A.; Faxneld, S.; Garbus, S. E.; Hellström, P.; Koschorreck, J.; lohrmann, N.; Roos, A.; Sellström, U.; Sonne, C.; Treu, G.; Vorkamp, K.; Yuan, B.; Eulaers, I. Organohalogen compounds of emerging concern in Baltic Sea biota: Levels, biomagnification potential and comparisons with legacy contaminants. Environ. Int. 2020, 144, 106037,  DOI: 10.1016/j.envint.2020.106037
      15
      Organohalogen compounds of emerging concern in Baltic Sea biota: Levels, biomagnification potential and comparisons with legacy contaminants
      de Wit, Cynthia A.; Bossi, Rossana; Dietz, Rune; Dreyer, Annekatrin; Faxneld, Suzanne; Garbus, Svend Erik; Hellstroem, Peter; Koschorreck, Jan; Lohmann, Nina; Roos, Anna; Sellstroem, Ulla; Sonne, Christian; Treu, Gabriele; Vorkamp, Katrin; Yuan, Bo; Eulaers, Igor
      Environment International (2020), 144 (), 106037CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
      While new chems. have replaced major toxic legacy contaminants such as polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), knowledge of their current levels and biomagnification potential in Baltic Sea biota is lacking. Therefore, a suite of chems. of emerging concern, including organophosphate esters (OPEs), short-chain, medium-chain and long-chain chlorinated paraffins (SCCPs, MCCPs, LCCPs), halogenated flame retardants (HFRs), and per- and polyfluoroalkyl substances (PFAS), were analyzed in blue mussel (Mytilus edulis), viviparous eelpout (Zoarces viviparus), Atlantic herring (Clupea harengus), gray seal (Halichoerus grypus), harbor seal (Phoca vitulina), harbor porpoise (Phocoena phocoena), common eider (Somateria mollissima), common guillemot (Uria aalge) and white-tailed eagle (Haliaeetus albicilla) from the Baltic Proper, sampled between 2006 and 2016. Results were benchmarked with existing data for legacy contaminants. The mean concns. for ΣOPEs ranged from 57 to 550 ng g-1 lipid wt. (lw), for ΣCPs from 110 to 640 ng g-1 lw for ΣHFRs from 0.42 to 80 ng g-1 lw, and for ΣPFAS from 1.1 to 450 ng g-1 wet wt. Perfluoro-4-ethylcyclohexanesulfonate (PFECHS) was detected in most species. Levels of OPEs, CPs and HFRs were generally similar or higher than those of polybrominated di-Ph ethers (PBDEs) and/or hexabromocyclododecane (HBCDD). OPE, CP and HFR concns. were also similar to PCBs and DDTs in blue mussel, viviparous eelpout and Atlantic herring. In marine mammals and birds, PCB and DDT concns. remained orders of magnitude higher than those of OPEs, CPs, HFRs and PFAS. Predator-prey ratios for individual OPEs (0.28-3.9) and CPs (0.40-5.0) were similar or somewhat lower than those seen for BDE-47 (5.0-29) and HBCDD (2.4-13). Ratios for individual HFRs (0.010-37) and PFAS (0.15-47) were, however, of the same order of magnitude as seen for p,p'-DDE (4.7-66) and CB-153 (31-190), indicating biomagnification potential for many of the emerging contaminants. Lack of toxicity data, including for complex mixts., makes it difficult to assess the risks emerging contaminants pose. Their occurrence and biomagnification potential should trigger risk management measures, particularly for MCCPs, HFRs and PFAS.
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    16. 16
      Driscoll, C. T.; Mason, R. P.; Man Chan, H.; Jacob, D. J.; Pirrone, N. Mercury as a Global Pollutant: Sources, Pathways, and Effects Terms of Use. Environ. Sci. Technol. 2013, 47, 39,  DOI: 10.1021/es305071v
      There is no corresponding record for this reference.
    17. 17
      HELCOM (2018b) Metals (lead, cadmium and mercury). HELCOM core indicator report.https://helcom.fi/media/core%20indicators/Metals-HELCOM-core-indicator-2018.pdf (accessed 2021-08-20).
      There is no corresponding record for this reference.
    18. 18
      Morel, F. M. M.; Kraepiel, A. M. L.; Amyot, M. The chemical cycle and bioaccumulation of mercury. Annu. Rev. Ecol Syst 1998, 29, 543– 566,  DOI: 10.1146/annurev.ecolsys.29.1.543
      There is no corresponding record for this reference.
    19. 19
      US-EPA. Method 7473 (SW-846): Mercury in Solids and Solutions by Thermal Decomposition, Amalgamation, and Atomic Absorption Spectrophotometry, rev. 0; US-EPA: Washington, DC, 1998; 17 pp (https://www.epa.gov/sites/production/files/2015-07/documents/epa-7473.pdf).
      There is no corresponding record for this reference.
    20. 20
      Bond, A. L.; Hobson, K. A. Reporting stable-isotope ratios in ecology: recommended terminology, guidelines, and best practices. Waterbirds 2012, 35, 324– 331,  DOI: 10.1675/063.035.0213
      There is no corresponding record for this reference.
    21. 21
      Post, D. M. Using stable isotopes to estimate trophic position: Models, methods, and assumptions. Ecology 2002, 83, 703– 718,  DOI: 10.1890/0012-9658(2002)083[0703:USITET]2.0.CO;2
      There is no corresponding record for this reference.
    22. 22
      Mizutani, H.; Kabaya, Y.; Wada, E. Nitrogen and Carbon Isotope Compositions relate linearly in Cormorant Tissues and its Diet. Isot Environ. Heal Stud 1991, 27, 166– 168
      There is no corresponding record for this reference.
    23. 23
      Kurle, C. M.; Sinclair, E. H.; Edwards, A. E.; Gudmundson, C. J. Temporal and spatial variation in the d15N and d13C values of fish and squid from Alaskan waters. Marine Biology 2011, 158, 2389– 2404,  DOI: 10.1007/s00227-011-1741-4
      There is no corresponding record for this reference.
    24. 24
      Fincel, M. J.; VanDeHey, J. A.; Wuestewald, A.; Chipps, S. R. Comparing isotope signatures of prey fish: does gut removal affect d13C or d15N?. Journal of Freshwater Ecology 2012, 27, 55– 62
      There is no corresponding record for this reference.
    25. 25
      Nakagawa, S.; Johnson, P. C. D.; Schielzeth, H. The coefficient of determination and intra-class correlation coefficient from generalized linear mixed-effects models revisited and expanded. J. R Soc. Interface 2017, 14, 20170213,  DOI: 10.1098/rsif.2017.0213
      There is no corresponding record for this reference.
    26. 26
      Nfon, E.; Cousins, I. T.; Järvinen, O.; Mukherjee, A. B.; Verta, M.; Broman, D. Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea. Sci. Total Environ. 2009, 407, 6267– 6274,  DOI: 10.1016/j.scitotenv.2009.08.032
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      Trophodynamics of mercury and other trace elements in a pelagic food chain from the Baltic Sea
      Nfon, Erick; Cousins, Ian T.; Jaervinen, Olli; Mukherjee, Arun B.; Verta, Matti; Broman, Dag
      Science of the Total Environment (2009), 407 (24), 6267-6274CODEN: STENDL; ISSN:0048-9697. (Elsevier B.V.)
      Mercury (Hg) and 13 other trace elements (Al, Ti, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were measured in phytoplankton, zooplankton, mysis and herring in order to examine the trophodynamics in a well-studied pelagic food chain in the Baltic Sea. The fractionation of nitrogen isotopes (δ 15N) was used to evaluate food web structure and to est. the extent of trophic biomagnification of the various trace elements. Trophic magnification factors (TMFs) for each trace element were detd. from the slope of the regression between trace element concns. and δ 15N. Calcd. TMFs showed fundamental differences in the trophodynamics of the trace elements in the pelagic food chain studied. Concns. of Al, Fe, Ni, Zn, Pb and Cd showed statistically significant decreases (TMF < 1) with increasing trophic levels and thus these trace elements tropically dil. or biodilute in this Baltic food chain. Cu, As, Cr, Mn, V, Ti and Co showed no significant relationships with trophic levels. Hg was unique among the trace elements studied in demonstrating a statistically significant increase (TMF > 1) in concn. with trophic level i.e. Hg biomagnifies in this Baltic food chain. The estd. TMF for Hg in this food chain was comparable to TMFs obsd. elsewhere for diverse food chains and locations.
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    27. 27
      Lavoie, R. A.; Jardine, T. D.; Chumchal, M. M.; Kidd, K. A.; Campbell, L. M. Biomagnification of Mercury in Aquatic Food Webs: A Worldwide Meta-Analysis. Environ. Sci. Technol. 2013, 47, 13385– 13394,  DOI: 10.1021/es403103t
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      Biomagnification of Mercury in Aquatic Food Webs: A Worldwide Meta-Analysis
      Lavoie, Raphael A.; Jardine, Timothy D.; Chumchal, Matthew M.; Kidd, Karen A.; Campbell, Linda M.
      Environmental Science & Technology (2013), 47 (23), 13385-13394CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      The slope of the simple linear regression between log10 transformed Hg concn. and stable N isotope values (δ15N), hereafter called trophic magnification slope (TMS), from several trophic levels in a food web can represent the overall degree of Hg biomagnification. We compiled data from 69 studies that detd. total Hg (THg) or MeHg TMS values in 205 aquatic food webs worldwide. Hg TMS values were compared against physicochem. and biol. factors hypothesized to affect Hg biomagnification in aquatic systems. Food webs ranged across 1.7±0.7 (mean ±SD) and 1.8±0.8 trophic levels (calcd. using δ15N from baseline to top predator) for THg and MeHg, resp. The av. trophic level (based on δ15N) of the upper-trophic-level organisms in the food web was 3.7±0.8 and 3.8±0.8 for THg and MeHg food webs, resp. For MeHg, the mean TMS value was 0.24±0.08 but varied from 0.08 to 0.53 and was, on av., 1.5 times higher than that for THg with a mean of 0.16±0.11 (range: -0.19 to 0.48). Both THg and MeHg TMS values were significantly and pos. correlated with latitude. TMS values in freshwater sites increased with dissolved org. C and decreased with total P and atm. Hg deposition. Results suggest that Hg biomagnification through food webs is highest in cold and low productivity systems; however, much of the among-system variability in TMS values remains unexplained. We identify crit. data gaps and provide recommendations for future studies that would improve our understanding of global Hg biomagnification.
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    28. 28
      Chen, C. Y.; Dionne, M.; Mayes, B. M.; Ward, D. M.; Sturup, S.; Jackson, B. P. Mercury bioavailability and bioaccumulation in estuarine food webs in the Gulf of Maine. Environ. Sci. Technol. 2009, 43, 1804– 1810,  DOI: 10.1021/es8017122
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      Mercury Bioavailability and Bioaccumulation in Estuarine Food Webs in the Gulf of Maine
      Chen, Celia Y.; Dionne, Michele; Mayes, Brandon M.; Ward, Darren M.; Sturup, Stefan; Jackson, Brian P.
      Environmental Science & Technology (2009), 43 (6), 1804-1810CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Marine food webs are important links between Hg in the environment and human exposure via consumption of fish. Estuaries contain sediment repositories of Hg and are also crit. habitat for marine fish and shellfish species consumed by humans. MeHg biotransfers from sites of prodn. in estuarine sediments to higher trophic levels via both benthic and pelagic pathways. The authors studied the potential for Hg biotransfer to estuarine food webs across a Hg contamination gradient in the Gulf of Maine. Despite the variation in sediment Hg concns. across sites ( > 100 fold), Hg concns. in biota ranged by only 2-4 fold for each species across sites. Sediment contamination alone explained some variation in Hg and MeHg concns. in biota across sites. However, biogeochem. and ecol. factors also explained significant variation in Hg bioaccumulation across species. Contaminated sites had higher total org. carbon concns. in sediments, which related to a decrease in Hg bioaccumulation (measured as biota-sediment concn. factors). Also, concns. of MeHg were higher in pelagic-feeding than benthic-feeding fauna (detd. from δ13C), indicating the importance of pelagic pathways in transferring MeHg. Lastly, the proportion of total Hg as MeHg increased with trophic level (measured as δ15N). These results reveal the importance of both biogeochem. and ecol. factors in detg. the bioavailability and trophic transfer of MeHg in estuarine food webs.
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    29. 29
      Chen, C. Y.; Borsuk, M. E.; Bugge, D. M.; Hollweg, T.; Balcom, P. H.; Ward, D. M.; Williams, J.; Mason, R. P. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast Unitd States. PLoS One 2014, 9, e89305,  DOI: 10.1371/journal.pone.0089305
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      Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the Northeast United States
      Chen, Celia Y.; Borsuk, Mark E.; Bugge, Deenie M.; Hollweg, Terill; Balcom, Prentiss H.; Ward, Darren M.; Williams, Jason; Mason, Robert P.
      PLoS One (2014), 9 (2), e89305/1-e89305/11, 11 pp.CODEN: POLNCL; ISSN:1932-6203. (Public Library of Science)
      Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concns. in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concns. in water column particulate material, but not in sediments, were predictive of MeHg concns. in fish (killifish and Atlantic silversides). Moreover, MeHg concns. were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concns. were only predictive of concns. of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that det. MeHg input and bioavailability in the water column.
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    30. 30
      Bradley, M. A.; Barst, B. D.; Basu, N. A review of mercury bioavailability in humans and fish. International Journal of Environmental Research and Public Health 2017, 14, 169,  DOI: 10.3390/ijerph14020169
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      A review of mercury bioavailability in humans and fish
      Bradley, Mark A.; Barst, Benjamin D.; Basu, Niladri
      International Journal of Environmental Research and Public Health (2017), 14 (2), 169/1-169/20CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
      To est. human exposure to methylmercury (MeHg), risk assessors often assume 95%-100% bioavailability in their models. However, recent research suggests that assuming all, or most, of the ingested mercury (Hg) is absorbed into systemic circulation may be erroneous. The objective of this paper is to review and discuss the available state of knowledge concerning the assimilation or bioavailability of Hg in fish and humans. In fish, this meant reviewing studies on assimilation efficiency, that is the difference between ingested and excreted Hg over a given period of time. In humans, this meant reviewing studies that mostly investigated bioaccessibility (digestive processes) rather than bioavailability (cumulative digestive + absorptive processes), although studies incorporating absorption for a fuller picture of bioavailability were also included where possible. The outcome of this review shows that in a variety of organisms and exptl. models that Hg bioavailability and assimilation is less than 100%. Specifically, 25 studies on fish were reviewed, and assimilation efficiencies ranged from 10% to 100% for MeHg and from 2% to 51% for Hg(II). For humans, 20 studies were reviewed with bioaccessibility ests. ranging from 2% to 100% for MeHg and 0.2% to 94% for Hg(II). The overall absorption ests. ranged from 12% to 79% for MeHg and 49% to 69% for Hg(II), and were consistently less than 100%. For both fish and humans, a no. of cases are discussed in which factors (e.g., Hg source, cooking methods, nutrients) are shown to affect Hg bioavailability. The summaries presented here challenge a widely-held assumption in the Hg risk assessment field, and the paper discusses possible ways forward for the field.
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    31. 31
      Hall, B. D.; Bodaly, R. A.; Fudge, R. J.; Rudd, J. W. M.; Rosenberg, D. M. Food as the dominant pathway of methylmercury uptake by fish. Water, Air and Soil Pollution 1997, 100, 13– 24,  DOI: 10.1023/A:1018071406537
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      Food as the dominant pathway of methylmercury uptake by fish
      Hall, B. D.; Bodaly, R. A.; Fudge, R. J. P.; Rudd, J. W. M.; Rosenberg, D. M.
      Water, Air, and Soil Pollution (1997), 100 (1-2), 13-24CODEN: WAPLAC; ISSN:0049-6979. (Kluwer Academic Publishers)
      A field expt. was conducted to det. the degree to which fish accumulated methylmercury (MeHg) via their food or via passive uptake from water through the gills. Finescale dace (Phoxinus neogaeus) were held in 2000 L enclosed pens floating in an undisturbed, oligotrophic lake in northwestern Ontario. Fish were exposed to water contg. either low (0.10-0.40 ng L-1), intermediate (0.45-1.30 ng L-1), or high (0.80-2.1 ng L-1) concns. of MeHg. Zooplankton with either low (0.16-0.18 μg g-1 d.w.) or high (0.28-0.76 μg g-1 d.w.) concns. of MeHg were added daily to each pen. Fish fed zooplankton with high concns. of MeHg had significantly higher concns. of mercury in muscle after 32 days than fish fed zooplankton with low concns. of MeHg. Fish feeding on zooplankton with low concns. of MeHg had the same amt. of Hg in their tissues as fish at the start of the expt. Uptake from water was at most 15%. This is the first expt. to confirm that food is the dominant pathway of MeHg bioaccumulation in fish at natural levels of MeHg.
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    32. 32
      Lankov, A.; Ojaveer, H.; Simm, M.; Põllupüü, M.; Möllmann, C. Feeding ecology of pelagic fish species in the Gulf of Riga (Baltic Sea): the importance of changes in the zooplankton community. J. Fish Biol. 2010, 77, 2268– 2284,  DOI: 10.1111/j.1095-8649.2010.02805.x
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      Feeding ecology of pelagic fish species in the Gulf of Riga (Baltic Sea): the importance of changes in the zooplankton community
      Lankov A; Ojaveer H; Simm M; Pollupuu M; Mollmann C
      Journal of fish biology (2010), 77 (10), 2268-84 ISSN:.
      The feeding ecology of four pelagic fish species was studied in relation to their prey availability in the Gulf of Riga (Baltic Sea) during the summer 1999-2006. The zooplankton community was dominated by the cladoceran Bosmina longispina, rotifers Keratella cochlearis and K. quadrata and the copepod Eurytemora affinis, with the highest interannual variability in abundance recorded for B. longispina. The last influenced the diet of adult sprat Sprattus sprattus, juvenile smelt Osmerus eperlanus and three-spined stickleback Gasterosteus aculeatus as these were strongly selecting for B. longispina. The fish feeding activity did not match the abundance dynamics of their preferred prey, suggesting that fishes may switch to consume other prey in case the preferred diet was limited. A considerable dietary overlap indicated high potential competition between pelagic fish species. While herring Clupea harengus membras and G. aculeatus were relying on very different food, the diets of young O. eperlanus and G. aculeatus were very similar. Interannual variability in zooplankton composition and abundance significantly affected the diet composition of fishes, but those changes were insufficient to exert a consistent influence upon fish feeding activity and total amounts of zooplankton consumed.
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    33. 33
      Jacobson, P.; Bengström, U.; Eklöf, J. Size-dependent diet composition and feeding of Eurasian perch (Perca fluviatilis) and northern pike (Esox lucius) in the Baltic Sea. Boreal. Environ. Res. 2019, 24, 137– 153
      There is no corresponding record for this reference.
    34. 34
      Bergström, U.; Olsson, J.; Casini, M.; Eriksson, B. K.; Fredriksson, R.; Weenhage, H.; Appelberg, M. Stickleback increase in the Baltic Sea - A thorny issue for coastal predatory fish. Estuar Coast Shelf Sci. 2015, 163, 134– 142,  DOI: 10.1016/j.ecss.2015.06.017
      There is no corresponding record for this reference.
    35. 35
      Griffiths, J. R.; Kadin, M.; Nascimento, F. J. A.; Tamelander, T.; Törnroos, A.; Bonaglia, S.; Bonsdorff, E.; Brüchert, V.; Gårdmark, A.; Järnström, M.; Kotta, J.; Lindegren, M.; Nordström, M. C.; Norkko, A.; Olsson, J.; Weigel, B.; Zydelis, R.; Blenckner, T.; Niiranen, S.; Winder, M. The importance of benthic–pelagic coupling for marine ecosystem functioning in a changing world. Glob. Chang. Biol. 2017, 23, 2179– 2196,  DOI: 10.1111/gcb.13642
      35
      The importance of benthic-pelagic coupling for marine ecosystem functioning in a changing world
      Griffiths Jennifer R; Nascimento Francisco J A; Winder Monika; Kadin Martina; Blenckner Thorsten; Niiranen Susa; Tamelander Tobias; Norkko Alf; Tornroos Anna; Bonsdorff Erik; Jarnstrom Marie; Nordstrom Marie C; Weigel Benjamin; Tornroos Anna; Lindegren Martin; Bonaglia Stefano; Bruchert Volker; Bonaglia Stefano; Gardmark Anna; Olsson Jens; Kotta Jonne; Norkko Alf; Zydelis Ramunas
      Global change biology (2017), 23 (6), 2179-2196 ISSN:.
      Benthic-pelagic coupling is manifested as the exchange of energy, mass, or nutrients between benthic and pelagic habitats. It plays a prominent role in aquatic ecosystems, and it is crucial to functions from nutrient cycling to energy transfer in food webs. Coastal and estuarine ecosystem structure and function are strongly affected by anthropogenic pressures; however, there are large gaps in our understanding of the responses of inorganic nutrient and organic matter fluxes between benthic habitats and the water column. We illustrate the varied nature of physical and biological benthic-pelagic coupling processes and their potential sensitivity to three anthropogenic pressures - climate change, nutrient loading, and fishing - using the Baltic Sea as a case study and summarize current knowledge on the exchange of inorganic nutrients and organic material between habitats. Traditionally measured benthic-pelagic coupling processes (e.g., nutrient exchange and sedimentation of organic material) are to some extent quantifiable, but the magnitude and variability of biological processes are rarely assessed, preventing quantitative comparisons. Changing oxygen conditions will continue to have widespread effects on the processes that govern inorganic and organic matter exchange among habitats while climate change and nutrient load reductions may have large effects on organic matter sedimentation. Many biological processes (predation, bioturbation) are expected to be sensitive to anthropogenic drivers, but the outcomes for ecosystem function are largely unknown. We emphasize how improved empirical and experimental understanding of benthic-pelagic coupling processes and their variability are necessary to inform models that can quantify the feedbacks among processes and ecosystem responses to a changing world.
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    36. 36
      Kiljunen, M.; Peltonen, H.; Lehtiniemi, M.; Uusitalo, L.; Sinisalo, T.; Norkko, J.; Kunnasranta, M.; Torniainen, J.; Rissanen, A. J.; Karjalainen, J. Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs. Limnol Oceanogr 2020, 65, 1706– 1722,  DOI: 10.1002/lno.11413
      36
      Benthic-pelagic coupling and trophic relationships in northern Baltic Sea food webs
      Kiljunen, Mikko; Peltonen, Heikki; Lehtiniemi, Maiju; Uusitalo, Laura; Sinisalo, Tuula; Norkko, Joanna; Kunnasranta, Mervi; Torniainen, Jyrki; Rissanen, Antti J.; Karjalainen, Juha
      Limnology and Oceanography (2020), 65 (8), 1706-1722CODEN: LIOCAH; ISSN:0024-3590. (John Wiley & Sons, Inc.)
      Understanding marine ecosystem structure and functioning is crucial in supporting sustainable management of natural resources and monitoring the health of marine ecosystems. The current study utilized stable isotope (SI) mixing models and trophic position models to examine energy flow, trophic relationships, and benthic-pelagic coupling between food web components. Roughly 1900 samples from different trophic levels in the food web, collected during 2001-2010 from four northern and central sub-basins of the Baltic Sea, were analyzed for SI ratios of carbon and nitrogen. Trophic structure of the food webs among the sub-basins was consistent, but there were differences between the proportions of energy in different trophic levels that had originated from the benthic habitat. Mysids and amphipods served as important links between the benthic and pelagic ecosystems. Much (35-65%) of their energy originated from the benthic zone but was transferred to higher trophic levels in the pelagic food web by consumption by herring (Clupea harengus). One percent to twenty-four percent of the energy consumption of apex seal predators (Halichoerus grypus and Pusa hispida) and predatory fish (Salmo salar) was derived from benthic zone. Diets of mysids and amphipods differed, although some overlap in their dietary niches was obsd. The food web in the Gulf of Finland was more influenced by the benthic subsystem than food webs in the other sub-basins. The baseline levels of δ13C and δ15N differed between sub-basins of the Baltic Sea, indicating differences in the input of org. matter and nutrients to each sub-basin.
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    37. 37
      Won, E. J.; Choi, B.; Hong, S.; Khim, J. S.; Shin, K. H. Importance of accurate trophic level determination by nitrogen isotope of amino acids for trophic magnification studies: A review. Environ. Pollut. 2018, 238, 677– 690,  DOI: 10.1016/j.envpol.2018.03.045
      37
      Importance of accurate trophic level determination by nitrogen isotope of amino acids for trophic magnification studies: A review
      Won, Eun-Ji; Choi, Bohyung; Hong, Seongjin; Khim, Jong Seong; Shin, Kyung-Hoon
      Environmental Pollution (Oxford, United Kingdom) (2018), 238 (), 677-690CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)
      During the last several decades, persistent org. pollutants and metals cause great concern for their toxicity in organisms as well as for their bioaccumulation and/or trophic transfer through the food chains in ecosystems. A large no. of studies therefore have focused on the trophic levels of organisms to illustrate food web structure, as a crit. component in the study of pollutant dynamics and biomagnification. The trends in biomagnification of pollutants in food webs indeed provide fundamental information about the properties and fates of pollutants in ecosystems. The trophic magnification supports the establishment of a reliable trophic structure, which can further aid the understanding of the transport and exposure routes of contaminants in accumulation and risk assessments. Recently, efforts to interpret the food web structure using carbon and nitrogen stable isotope ratios have contributed to better understanding of the fate of pollutants in the ecosystem. However, it is known that this isotope anal. of bulk ones has many weaknesses, particularly for uncertainties on the est. of trophic levels and therefore of magnification factors for studied organisms, enough to support a regulatory interpretation. In this review, we collate studies that investigated biomagnification characteristics of pollutants in aquatic ecosystems, along with calcd. trophic magnification factors. Moreover, we introduce a novel approach, compd.-specific stable isotope anal. of nitrogen in amino acids, to establish reliable food web structures and accurate trophic levels for biomagnification studies. This method promises to provide sound results for interpreting the influence of the pollutant in organisms, along with their bioaccumulation and magnification characteristics, as well as that in ecosystem.
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    38. 38
      Elliott, H.; Braune, B. M.; Elliott, J. E. Beyond bulk δ15N: Combining a suite of stable isotopic measures improves the resolution of the food webs mediating contaminant signals across space, time and communities. Environ. Int. 2021, 148, 106370,  DOI: 10.1016/j.envint.2020.106370
      38
      Beyond bulk d15N: Combining a suite of stable isotopic measures improves the resolution of the food webs mediating contaminant signals across space, time and communities
      Elliott, Kyle H.; Braune, Birgit M.; Elliott, John E.
      Environment International (2021), 148 (), 106370CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
      Top predators are used as indicators of contaminant trends across space and time. However, signals are integrated over complex food webs, and variation in diet may confound such signals. Trophic position, assessed by bulk δ15N, is widely used to infer the variation in diet relevant to contamination, yet a single variable cannot completely describe complex food webs. Thus, we examd. relationships across three aquatic systems varying from a single species to a small food web using bulk values from four isotopes and 21 amino acid-specific values. Because variation in baseline ('source') δ15N can confound ests. of trophic position , we calcd. trophic position from the difference between δ15Ntrophic (δ15N for amino acids that change with trophic position) and δ15Nsource (δ15N for amino acids that do not change with trophic position). Across all three systems, variation in δ15Nsource explained over half of the variation in bulk δ15N, and stable isotope values that reflected the base of the food web (δ13C, δ18O, δ34S) predicted contaminants as well or better than δ15N-which was supported by a meta-anal. of other studies. In ospreys feeding in lakes, variation in δ15Nsource across space created a spurious relationship between ΣDDT and apparent trophic position, and masked a relationship between ΣPCB and trophic position. In a seabird guild, changes in diet over time obscured temporal variation in contaminants over five decades. In Arctic fish and invertebrates, more accurate trophic magnification factors were calcd. using δ15Ntrophic-source. Thus, (1) using δ15Ntrophic-source, instead of bulk δ15N, avoided incorrect conclusions and improved accuracy of trophic magnification factors necessary to assess risk to top predators; and (2) diet assessed with multiple spatial isotopes, rather than δ15N alone, was essential to understand patterns in contaminants across space, time and biol. communities. Trophic position was most important for lipophilic 'legacy' contaminants (ΣDDT, ΣPCB) and habitat was most important for other contaminants (ΣPBDE, ΣPFAS, mercury). We argue that the use of amino acid-specific anal. of δ15N alongside 'non-trophic' isotopes should be a core feature of any study that examines the influence of trophic position on chem. pollution, as required for a chem. to be added to international conventions such as the Stockholm Convention.
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    39. 39
      Isomursu, M.; Koivusaari, J.; Stjernberg, T.; Hirvelä-Koski, V.; Venäläinen, E.-R. Lead poisoning and other human-related factors cause significant mortality in white-tailed eagles. Ambio 2018, 1– 11
      There is no corresponding record for this reference.
    40. 40
      Borgå, K.; Fisk, A. T.; Hoekstra, P. F.; Muir, D. C. G. Biological and chemical factors of importance in the bioaccumulation and trophic transfer of persistent organochlorine contaminants in arctic marine food webs. Environ. Toxicol. Chem. 2004, 23, 2367– 2385,  DOI: 10.1897/03-518
      40
      Biological and chemical factors of importance in the bioaccumulation and trophic transfer of persistent organochlorine contaminants in Arctic marine food webs
      Borga, Katrine; Fisk, Aaron T.; Hoekstra, Paul F.; Muir, Derek C. G.
      Environmental Toxicology and Chemistry (2004), 23 (10), 2367-2385CODEN: ETOCDK; ISSN:0730-7268. (SETAC Press)
      A review is given. Recent studies of arctic marine food webs have provided detailed insights regarding the biol. and chem. factors that influence the bioaccumulation and trophic transfer of persistent organochlorine (OC) contaminants in aquatic systems. This paper summarizes the recent literature with an emphasis on identifying important ecol. factors for explaining variability of OC concns. among organisms. The Arctic ecosystem has a no. of unique attributes, including long food chains, reduced diversity of species, similar food webs across the entire region, and limited influence from pollution point sources. Lipid content, body size, age, gender, reprodn., habitat use, migration, biotransformation, seasonal changes in habitat conditions, feeding ecol., and trophic position have all been demonstrated to influence OC concns. and bioaccumulation in arctic marine biota. The relative importance of each factor varies among OCs and organisms. Diet or trophic level is the dominant factor influencing OC concns. and dynamics in seabirds and marine mammals, although biotransformation can significantly influence nonrecalcitrant OCs, such as hexachlorocyclohexane isomers. Dietary accumulation of OCs is also an important route of exposure for arctic fish and zooplankton, and biomagnification of OCs may also occur among these organisms. To date, only limited attempts have been made to model trophic transfer of OCs in the arctic marine food web. Although models developed to assess OC dynamics in aquatic food webs have included some biol. variables (e.g., lipid content, feeding rate, diet compn., and growth rate), selection of processes included in these models as well as their math. solns. and parameterization all introduce simplification. This reduces biol. validity of the models and may be particularly problematic in a highly seasonal environment, such as the Arctic Ocean.
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    41. 41
      Gobas, F. A.P.C.; de Wolf, W.; Burkhard, L. P.; Verbruggen, E.; Plotzke, K. Revisiting bioaccumulation criteria for POPs and PBT assessments. Integ Environ. Assess Manag 2009, 5, 624– 637,  DOI: 10.1897/IEAM_2008-089.1
      41
      Revisiting bioaccumulation criteria for POPs and PBT assessments
      Gobas, Frank A. P. C.; de Wolf, Watze; Burkhard, Lawrence P.; Verbruggen, Eric; Plotzke, Kathleen
      Integrated Environmental Assessment and Management (2009), 5 (4), 624-637CODEN: IEAMCK; ISSN:1551-3777. (Society of Environmental Toxicology and Chemistry)
      A review. Scientists from academia, industry, and government reviewed current international regulations for the screening of com. chems. for bioaccumulation in the context of the current state of bioaccumulation science. On the basis of this review, several recommendations were proposed, including a scientific definition for "bioaccumulative substances," improved criteria for the characterization of bioaccumulative substances (including the trophic magnification factor and the biomagnification factor), novel methods for measuring and calcg. bioaccumulation properties, and a framework for screening com. chems. for bioaccumulative substances. The proposed framework for bioaccumulation screening improves current practices by reducing miscategorization, making more effective use of available bioaccumulation data that currently cannot be considered, reducing the need for animal testing, providing simpler and cheaper test protocols for animal studies in case animal studies are necessary, making use of alternative testing strategies, including in vitro and in silico metabolic transformation assays, and providing a scientific foundation for bioaccumulation screening that can act to harmonize bioaccumulation screening among various jurisdictions.
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    42. 42
      Dietz, R.; Fort, J.; Sonne, C.; Albert, C.; Bustnes, J. O.; Christensen, T. K.; Ciesielski, T. M.; Danielsen, J.; Dastnai, S.; Eens, M.; Erikstad, K. E.; Galatius, A.; Garbus, S. E.; Gilg, O.; Hanssen, S. E.; Helander, B.; Helberg, M.; Jaspers, V. L. B.; Jenssen, B. M.; Jonsson, J. E.; Kauhala, K.; Kolbeinsson, Y.; Kyhn, L. A.; Labansen, A. L.; Larsen, M. M.; Linstrøm, U.; Reiertsen, T. K.; Rigét, F. F.; Roos, A.; Strand, J.; Strøm, H.; Sveegaard, S.; Søndergaard, J.; Sun, J.; Teilmann, J.; Therkildsen, O. R.; Thórarinsson, T. L.; Tjørnløv, R. S.; Wilson, S.; Eulaers, I. A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves. Environ. Int. 2021, 146, 106178,  DOI: 10.1016/j.envint.2020.106178
      42
      A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves
      Dietz, Rune; Fort, Jerome; Sonne, Christian; Albert, Celine; Bustnes, Jan Ove; Christensen, Thomas Kjaer; Ciesielski, Tomasz Maciej; Danielsen, Johannis; Dastnai, Sam; Eens, Marcel; Erikstad, Kjell Einar; Galatius, Anders; Garbus, Svend-Erik; Gilg, Olivier; Hanssen, Sveinn Are; Helander, Bjorn; Helberg, Morten; Jaspers, Veerle L. B.; Jenssen, Bjoern Munro; Jonsson, Jon Einar; Kauhala, Kaarina; Kolbeinsson, Yann; Kyhn, Line Anker; Labansen, Aili Lage; Larsen, Martin Moerk; Lindstoem, Ulf; Reiertsen, Tone K.; Riget, Frank F.; Roos, Anna; Strand, Jakob; Stroem, Hallvard; Sveegaard, Signe; Soendergaard, Jens; Sun, Jiachen; Teilmann, Jonas; Therkildsen, Ole Roland; Thorarinsson, Thorkell Lindberg; Tjoernloev, Rune Skjold; Wilson, Simon; Eulaers, Igor
      Environment International (2021), 146 (), 106178CODEN: ENVIDV; ISSN:0160-4120. (Elsevier Ltd.)
      A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geog. focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concns. within the High Risk Category (HRC) and Severe Risk Category (SRC). The corresponding percentages for seabirds, fish and bivalves were 2.7%, 25% and 8.0%, resp., although fish and bivalves were not represented in the SRC. Juveniles from all species showed to be at no or low risk. In comparison to the same species in the adjacent waters, i.e. the Greater North Sea and the North Atlantic, the estd. risk for Baltic populations is not considerably higher. These findings suggest that over the past few decades the Baltic Sea has improved considerably with respect to presenting Hg exposure to its local species, while it does still carry a legacy of elevated Hg levels resulting from high neighboring industrial and agricultural activity and slow water turnover regime.
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    43. 43
      HELCOM. Inputs of hazardous substances to the Baltic Sea. Baltic Sea Environmental Proceedings No. 162; Baltic Marine Environment Protection Commission, 2018a.
      There is no corresponding record for this reference.

  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c03846.

    • Methods and discussion of primary producer and trophic positions of the species, literature references on the diet of the study species, Tables S1–S7 with additional information on the sampling, summary statistics, and full biomagnification factors (PDF)


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